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  • 1.
    Barrirero, Jenifer
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan. Saarland University, Saarbrücken, Germany.
    Engstler, Michael
    Saarland University, Saarbrücken, Germany.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    de Jonge, Niels
    Saarland University, Saarbrücken, Germany.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Muecklich, Frank
    Saarland University, Saarbrücken, Germany.
    Comparison of segregations formed in unmodified and Sr-modified Al-Si alloys studied by atom probe tomography and transmission electron microscopy2014Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 611, s. 410-421Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanical properties of Al-7 wt.% Si can be enhanced by structural modifications of its eutectic phase. Addition of low concentrations of certain elements, in this case 150 wt-ppm Sr, is enough to cause a transition from a coarse plate-like Si structure to a finer coralline one. To fully understand the operating mechanism of this modification, the composition of the eutectic Si phase in unmodified and Sr-modified alloys was analysed and compared by atom probe tomography and (scanning) transmission electron microscopy. The unmodified alloy showed nanometre sized Al-segregations decorating defects, while the Sr-modified sample presented three types of Al-Sr segregations: (1) rod-like segregations that promote smoothening of the Al-Si boundaries in the eutectic phase, (2) particle-like segregations comparable to the ones seen in the unmodified alloy, and (3) planar segregations favouring the formation of twin boundaries. Al and Sr solubilities in Si after solidification were determined to be 430 +/- 160 at-ppm and 40 +/- 10 at-ppm, respectively. Sr predominantly segregates to the Si phase confirming its importance in the modification of the eutectic growth.

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  • 2.
    Barrirero, Jenifer
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. University of Saarland, Germany.
    Li, Jiehua
    University of Leoben, Austria.
    Engstler, Michael
    University of Saarland, Germany.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Schumacher, Peter
    University of Leoben, Austria.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Muecklich, Frank
    University of Saarland, Germany.
    Cluster formation at the Si/liquid interface in Sr and Na modified Al-Si alloys2016Ingår i: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 117, s. 16-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Atom probe tomography was used to compare Na and Sr modified Al-Si hypoeutectic alloys. Both Na and Sr promote the formation of nanometre-sized clusters in the Si eutectic phase. Compositional analyses of the clusters show an Al:Sr ratio of 2.92 +/- 0.46 and an Al:Na ratio of 1.07 +/- 0.23. It is proposed that SrAl2Si2 and NaAlSi clusters are formed at the Si/liquid interface and take part in the modification process by altering the eutectic Si growth.

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  • 3.
    Barrirero, Jenifer
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. Saarland Univ, Germany.
    Pauly, C.
    Saarland Univ, Germany.
    Engstler, M.
    Saarland Univ, Germany.
    Ghanbaja, J.
    Univ Lorraine, France.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Li, J.
    Univ Leoben, Austria.
    Schumacher, P.
    Univ Leoben, Austria.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Muecklich, F.
    Saarland Univ, Germany.
    Eutectic modification by ternary compound cluster formation in Al-Si alloys2019Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikel-id 5506Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Al-alloys with Si as the main alloying element constitute the vast majority of Al castings used commercially today. The eutectic Si microstructure in these alloys can be modified from plate-like to coral-like by the addition of a small amount of a third element to improve ductility and toughness. In this investigation the effects of Eu and Yb are studied and their influence on the microstructure is compared to further understand this modification. The two elements impact the alloy differently, where Eu modifies Si into a coral-like structure while Yb does not. Atom probe tomography shows that Eu is present within the Si phase in the form of ternary compound Al2Si2Eu clusters, while Yb is absent in the Si phase. This indicates that the presence of ternary compound clusters within Si is a necessary condition for the formation of a coral-like structure. A crystallographic orientation relationship between Si and the Al2Si2Eu phase was found, where the following plane normals are parallel: 011(Si) //0001(Al2Si2Eu), 111(Si)//6 (7) over bar 10(Al2Si2Eu) and 011(Si)//6 (7) over bar 10(Al2Si2Eu). No crystallographic relationship was found between Si and Al2Si2Yb. The heterogeneous formation of coherent Al2Si2Eu clusters inside the Si-phase is suggested to trigger the modification of the microstructure.

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  • 4.
    Birch, Jens
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Joelsson, Torbjörn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Single crystal CrN/ScN superlattice soft X-ray mirrors: epitaxial growth, structure, and properties2006Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 514, nr 1-2, s. 10-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Single crystal CrN/ScN superlattice films with modulation periods of 1.64 nm were grown on MgO(001) substrates. By utilizing a magnetically enhanced plasma in the vicinity of the substrate and a negative substrate bias, ion/metal nitride flux ratios of 45 and 144 were achieved during deposition of CrN and ScN, respectively. The effects of ion energies in the range [16–58 eV] and substrate temperatures in the range [535–853 °C] on the composition, interface width, crystal quality, and microstructure evolution were investigated using elastic recoil detection analysis, hard X-ray reflectivity, X-ray diffraction, and transmission electron microscopy (TEM). Minimal interface widths of 0.2 nm = 1/2 nitride unit cell were achieved at a growth temperature of 735 °C and ion energies of 24 and 28 eV for CrN and ScN, respectively. Under these conditions, also an optimum in the crystal quality was observed for near stoichiometric composition of CrN and ScN. TEM confirmed a cube-on-cube epitaxial relationship for the system with CrN(001)ScN(001)MgO(001) and CrN[100]ScN[100]MgO[100]. Also, the layers were coherently strained to each other with no misfit dislocations, threading dislocations, surface cusps, voids or gas bubbles present. Higher ion energies or lower deposition temperatures gave over-stoichiometric films with poor superlattice modulation while higher growth temperatures yielded a decreased crystal quality, due to loss of N. As-deposited superlattices with only 61 periods exhibited an absolute soft X-ray reflectance of 6.95% at an energy of 398.8 eV (Sc 2p-absorption edge) which is comparable to the performance of Cr/Sc. The compositional modulation and phase structure was stable during extended annealing at 850 °C, which is the highest thermal stability for an X-ray multilayer mirror. It is concluded that the ScN layers serve as effective diffusion barriers to hinder decomposition of the CrN layers and stabilize the pseudomorphic superlattice structure. Nanoindentation experiments showed that the hardness of the CrN/ScN superlattice films was 19 GPa.

  • 5.
    Chen, Yu-Hsiang
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Rongström, L.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Ostach, D.
    HZG, Germany.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Johansson-Jöesaar, Mats P
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. SECO Tools AB, Sweden.
    Schell, N.
    HZG, Germany.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Effects of decomposition route and microstructure on h-AlN formation rate in TiCrAlN alloys2017Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 691, s. 1024-1032Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The phase evolution of cubic (c), solid solution TixCr-0.37Al1-0.37-x N alloys with x = 0.03 and 0.16, and the kinetics of the hexagonal (h)-AlN formation are studied via in situ wide angle x-ray scattering experiments during high temperature (1000-1150 degrees C) annealing. Spinodal decomposition was observed in Ti0.16Cr0.36Al0.48N while Ti0.03Cr0.38Al0.59N decomposes through nucleation and growth of h-AlN, c-TiN and c-CrAlN. h-AlN is formed from c-CrAlN domains in both cases and the formation rate of h-AlN depends on the stability of the c-CrAlN domains. In Ti0.16Cr0.36Al0.48N, the c-CrAlN domains are stabilized by crystallographic coherency with the surrounding c-TiCrN in a microstructure originating from spinodal decomposition. This results in lower formation rates of h-AlN for this composition. These differences are reflected in higher activation energy for h-AlN formation in Ti0.16Cr0.36Al0.48N compared to Ti0.03Cr0.38Al0.59N. It also points out different stabilities of the intermediate phase c-CrAlN during phase decomposition of TiCrAlN alloys. Additional contributions to the low activation energy for formation of h-AlN in Ti0.03Cr0.38Al0.59N stems from precipitation at grain boundaries. (C) 2016 Elsevier B.V. All rights reserved.

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  • 6.
    Dalibon, Eugenia. L.
    et al.
    UTN, Argentina.
    Czerwiec, Thierry
    Univ Lorraine, France.
    Trava-Airoldi, Vladimir J.
    INPE, Brazil.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Bruhl, Sonia P.
    UTN, Argentina.
    Characterization of DLC coatings over nitrided stainless steel with and without nitriding pre-treatment using annealing cycles2019Ingår i: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMRandT, ISSN 2238-7854, Vol. 8, nr 2, s. 1653-1662Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Amorphous hydrogenated diamond-like carbon (DLC) coatings were deposited using plasma assisted chemical vapour deposition (PACVD) on precipitation hardening (PH) stainless steel.Plasma nitriding has been used as pre-treatment to enhance adhesion and mechanical properties. Chemical and mechanical properties of DLC coatings are dependent on the hydrogen content and so on the relation between sp(3)/sp(2) bondings. The bondings and the structure of the DLC film change with temperature. In this work, a study of the thermal degradation and the evolution of the mechanical properties of DLC coatings over PH stainless steel have been carried out, including the effect of an additional nitrided layer. Nitrided and non-nitrided steel samples were subjected to the same coated in the same conditions, and they were submitted to the same thermal cycles, heating from room temperature to 600 degrees C in several steps. After each cycle, Raman spectra and surface topography measurements were performed and analyzed. Nanohardness measurements and tribological tests, using a pin-on-disc machine, were carried out to analyze variations in the friction coefficient and the wear resistance. The duplex sample, with nitriding as pre-treatment showed a better thermal stability. For duplex sample, the coating properties, such as adhesion, and friction coefficient were sustained after annealing at higher temperatures; whereas it was not the case for only coated sample. (C) 2018 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda.

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  • 7.
    Dalibon, Eugenia L.
    et al.
    University of Tecnol Nacl UTN FRCU, Argentina.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Trava-Airoldi, Vladimir J.
    INPE, Brazil.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Bruhl, Sonia P.
    University of Tecnol Nacl UTN FRCU, Argentina.
    Carbon Based Coatings Deposited on Nitrided Stainless Steel: Study of Thermal Degradation2017Ingår i: PROCEEDINGS OF THE 3RD PAN AMERICAN MATERIALS CONGRESS, SPRINGER INTERNATIONAL PUBLISHING AG , 2017, s. 57-66Konferensbidrag (Refereegranskat)
    Abstract [en]

    Amorphous hydrogenated carbon (DLC) coatings have a high hardness depending on the relative amount of sp(3)/sp(2) bondings. They also exhibit an extremely low friction coefficient and are chemically inert. However, these coatings have some disadvantages which limit their applications. For instance, adhesion is poor when they are deposited on metallic substrates and they are also unstable at high temperatures, degrading into graphite and loosing hardness. In this work, DLC coatings were deposited on precipitation hardening stainless steel (PH Corrax) which was plasma nitrided before the coating deposition. The samples were submitted to annealing treatments for an hour at different temperatures from 200 to 600 degrees C, together with a control group, which was only coated but not nitrided. After each annealing cycle, Raman Spectroscopy, nanoindentation and microscopy were used to check film properties. It was demonstrated that the nitriding pre treatment improved not only adhesion but also the thermal stability of the DLC, slowing degradation and preventing delamination.

  • 8.
    Eriksson, Anders
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Näslund, Lars-Åke
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Johansson, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Sjölen, J.
    Seco Tools AB, Fagersta, Sweden.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Arc deposition of Ti–Si–C–N thin films from binary and ternary cathodes — Comparing sources of C2012Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 213, s. 145-154Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ti–Si–C–N thin films with composition of 1–11 at.% Si and 1–20 at.% C have been deposited onto cemented carbide substrates by arcing Ti–Si cathodes in a CH4 + N2 gas mixture and, alternatively, through arcing Ti–Si–C cathodes in N2. Films of comparable compositions from the two types of cathodes have similar structure and properties. Hence, C can be supplied as either plasma ions generated from the cathode or atoms from the gas phase with small influence on the structural evolution. Over the compositional range obtained, the films were dense and cubic-phase nanocrystalline, as characterized by X-ray diffraction, ion beam analysis, and scanning and transmission electron microscopy. The films have high hardness (30–40 GPa by nanoindentation) due to hardening from low-angle grain boundaries on the nanometer scale and lattice defects such as growth-induced vacancies and alloying element interstitials.

  • 9.
    Eriksson, Anders
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Zhu, Jianqiang
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Johansson, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan. Seco Tools AB, Sweden.
    Sjölen, Jacob
    Seco Tools AB, Sweden.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ti-Si-C-N Thin Films Grown by Reactive Arc Evaporation from Ti3SiC2 Cathodes2011Ingår i: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 26, s. 874-881Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ti-Si-C-N thin films were deposited onto WC-Co substrates by industrial scale arc evaporation from Ti3SiC2 compound cathodes in N2 gas. Microstructure and hardness were found to be highly dependent on the wide range of film compositions attained, comprising up to 12 at.% Si and 16 at.% C. Nonreactive deposition yielded films consisting of understoichiometric TiCx, Ti and silicide phases with high (27 GPa) hardness. At a nitrogen pressure of 0.25-0.5 Pa, below that required for N saturation, superhard, 45-50 GPa, (Ti,Si)(C,N) films with a nanocrystalline feathered structure were formed. Films grown above 2 Pa displayed crystalline phases of more pronounced nitride character, but with C and Si segregated to grain boundaries to form weak grain boundary phases. In abundance of N, the combined presence of Si and C disturb cubic phase growth severely and compromises the mechanical strength of the films.

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  • 10.
    Eriksson, Anders
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Zhu, Jianqiang
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Johansson, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan. Seco Tools AB, Sweden.
    Sjölen, Jacob
    Seco Tools AB, Sweden.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Layer Formation by Resputtering in Ti-Si-C Hard Coatings during Large Scale Cathodic Arc Deposition2011Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, nr 15, s. 3923-3930Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the physical mechanism behind the phenomenon of self-layering in thin films made by industrial scale cathodic arc deposition systems using compound cathodes and rotating substrate fixture. For Ti-Si-C films, electron microscopy and energy dispersive x-ray spectrometry reveals a trapezoid modulation in Si content in the substrate normal direction, with a period of 4 to 23 nm dependent on cathode configuration. This is caused by preferential resputtering of Si by the energetic deposition flux incident at high incidence angles when the substrates are facing away from the cathodes. The Ti-rich sub-layers exhibit TiC grains with size up to 5 nm, while layers with high Si-content are less crystalline. The nanoindentation hardness of the films increases with decreasing layer thickness.

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  • 11.
    Eriksson, Fredrik
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Reflectivity and structural evolution of Cr/Sc and nitrogen containing Cr/Sc multilayers during thermal annealing2008Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 104, nr 6, s. 063516-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is shown that the thermal stability in vacuum of Cr/Sc multilayer thin films used as reflective optical components in soft x-ray instrumentation has substantial dependence on incorporation of N. The thermal stability is increased by incorporating 34 at.% of N in Cr/Sc multilayers. A pure Cr/Sc multilayer x-ray mirror starts a continuous degradation already at ~100 °C with a complete destruction of the multilayer at 500 °C. The resulting structure is a mixture of Cr and Sc nanocrystallites. The degradation can be described by linear diffusion theory and is suggested to be due to the formation of uniformly distributed phase-separated nanocrystallites followed by an Ostwald ripening process with an apparent activation energy of 0.5 eV. At the multilayer-substrate interface, a 7 nm thin Sc-Si layer is formed which effectively hinders indiffusion of Si and outdiffusion of Cr and Sc. A nitrided multilayer, initially consisting of crystalline fcc CrNx and fcc ScNy layers (x and y<1), is observed to improve in structural quality up to ~250 °C where it is stable for more than 12 h. At ~330 °C, the multilayer separates into regions with two multilayer periods, differing by less than 0.04 nm, which are stable at 420 °C over an extended period of time >40 h. It is proposed that the separation into the different multilayer periods is a consequence of redistribution of N within the Cr layers. Sc is observed to be stabilized in the ScN layers, which, in turn, inhibit the formation of a Sc-Si barrier layer at the substrate leading to a strong exchange of Si and Cr across the film substrate. This leads to a Cr-Si/ScN layered structure close to the substrate and chromium silicide crystallites inside the substrate. Close to the top of the multilayer, a CrN/ScN multilayer appears to be retained.

  • 12.
    Eriksson, Fredrik
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ostach, Daniel
    Helmholtz Zentrum Geesthacht, Germany.
    Schell, Norbert
    Helmholtz Zentrum Geesthacht, Germany.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ion-assisted magnetron sputter deposition of B4C doped Ni/Ti multilayer mirrors2018Ingår i: ADVANCES IN X-RAY/EUV OPTICS AND COMPONENTS XIII, SPIE-INT SOC OPTICAL ENGINEERING , 2018, Vol. 10760, artikel-id UNSP 1076006Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ion-assisted magnetron sputter deposition have been used to deposit Ni/Ti multilayer neutron mirrors. Improved interface widths were obtained by using B4C doping, to eliminate nanocrystallites by amorphization, and a two-stage modulated ion assistance, to obtain abrupt and smooth interfaces. In situ high-energy wide angle X-ray scattering during multilayer depositions was used to monitor the microstructure evolution and to determine the most favourable growth conditions. Post growth X-ray reflectometry in combination with high resolution transmission electron microscopy confirmed the amorhization and revealed significant improvements in interface widths and reduction of kinetic roughening upon applying B4C doping and modulated ion assistance during growth. Significant improvement of neutron supermirror performance is predicted by employing this technique.

  • 13.
    Eriksson, Fredrik
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Schäfers, F.
    Gullikson, E. M.
    Aouadi, S.
    Rohde, S.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Atomic scale interface engineering by modulated ion-assisted deposition applied to soft x-ray multilayer optics2008Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 47, nr 23, s. 4196-4204Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cr/Sc and Ni/V multilayers, intended as normal incidence soft x-ray mirrors and Brewster angle polarizers, have been synthesized by employing a novel modulated low-energy and high-flux ion assistance as a means of engineering the interfaces between the subnanometer layers on an atomic scale during magnetron sputter deposition. To reduce both roughness and intermixing, the ion energy was modulated within each layer. The flat and abrupt interfaces yielded soft x-ray mirrors with near-normal incidence reflectances of R = 20.7% at the Sc 2p absorption edge and R = 2.7% at the V 2p absorption edge. Multilayers optimized for the Brewster angle showed a reflectance of R = 26.7% and an extinction ratio of Rs/Rp=5450 for Cr/Sc and R = 10% and Rs/Rp=4190 for Ni/V. Transmission electron microscopy investigations showed an amorphous Cr/Sc structure with an accumulating high spatial frequency roughness. For Ni/V the initial growth mode is amorphous and then turns crystalline after ~1/3 of the total thickness, with an accumulating low spatial frequency roughness as a consequence. Elastic recoil detection analyses showed that N was the major impurity in both Cr/Sc and Ni/V with concentrations of 15 at. % and 9 at. %, respectively, but also O (3 at. % and 1.3 at. %) and C (0.5 at. % and 1.9 at. %) were present. Simulations of the possible normal incidence reflective properties in the soft x-ray range of 100-600 eV are given, predicting that reflectivities of more than 31% for Cr/Sc and 5.8% for Ni/V can be achieved if better control of the impurities and the deposition process is employed. The simulations also show that Cr/Sc is a good candidate for mirrors for the photon energies between the absorption edges of B (E = 188 eV) and Sc (E = 398.8 eV).

  • 14.
    Eriksson, Fredrik
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Schäfers, Franz
    Gullikson, Eric M.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Interface engineering of short-period Ni/V multilayer X-ray mirrors2006Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 500, nr 1-2, s. 84-95Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Low-energy ion-assisted magnetron sputter deposition has been used for the synthesis of highly reflective Ni/V multilayer soft X-ray mirrors. A low ion energy and a high ion-to-metal flux ratio were employed in order to stimulate the adatom mobility while minimizing ion-induced intermixing at the interfaces. An analytic model, based on the binary collision approximation, was used in order to gain insight into low-energy ion-surface interactions as a function of ion energy and ion-to-metal flux ratio. The model predicted a favorable region in the ion energy-flux parameter space where only surface atomic displacements are stimulated during growth of Ni and V for multilayers. For a series of Ni/V multilayer mirrors with multilayer periods about Λ = 1.2 nm, grown with a continuous ion assistance using energies in the range 7-36 eV and with ion-to-metal flux ratios ΦNi = 4.7 and ΦV=20.9, specular and diffuse X-ray scattering analyses revealed that ion energies of ∼27-31 eV produced the best trade-off between reduced interfacial roughness and intermixing. However, it was also concluded that an interface mixing of about ± 1 atomic distance is unavoidable when a continuous flux of assisting ions is used. To overcome this limitation, a sophisticated interface engineering technique was employed, where the first 0.3 nm of each layer was grown with a high-flux low-energy ion assistance and the remaining part was grown with a slightly higher ion energy. This method was demonstrated to largely eliminate the intermixing while maintaining the smoothening effect of ion assistance. Two Ni/V multilayer soft X-ray mirror structures, one with 500 periods designed for near-normal incidence and one 150 periods reflecting polarizer at the Brewster angle, were grown utilizing the interface engineering concept. Both the near-normal incidence reflectivity as well as polarizability were improved by a factor of 2 as compared to previously reported data for an X-ray energy of E = 511 eV. © 2005 Elsevier B.V. All rights reserved.

  • 15.
    Fallqvist, Amie
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Fager, Hanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Self-organization during Growth of ZrN/SiNx Multilayers by Epitaxial Lateral Overgrowth2013Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 114, nr 224302Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    ZrN/SiNx nanoscale multilayers were deposited on ZrN seed layers grown on top of MgO(001) substrates by dc magnetron sputtering with a constant ZrN thickness of 40 Å and with an intended SiNx thickness of 2, 4, 6, 8, and 15 Å at a substrate temperature of 800 °C and 6 Å at 500 °C. The films were investigated by X-ray diffraction, high-resolution scanning transmission electron microscopy, and energy dispersive X-ray spectroscopy. The investigations show that the SiNx is amorphous and that the ZrN layers are crystalline. Growth of epitaxial cubic SiNx – known to take place on TiN(001) – on ZrN(001) is excluded to the monolayer resolution of this study. During the course of SiNx deposition, the material segregates to form surface precipitates in discontinuous layers for SiNx thicknesses ≤ 6 Å that coalesce into continuous layers for 8 and 15 Å thickness at 800 °C, and for 6 Å at 500 °C. The SiNx precipitates are aligned vertically. The ZrN layers in turn grow by epitaxial lateral overgrowth on the discontinuous SiNx in samples deposited at 800 °C with up to 6 Å thick SiNx layers. Effectively a self-organized nanostructure can be grown consisting of strings of 1-3 nm large SiNx precipitates along apparent column boundaries in the epitaxial ZrN.

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  • 16.
    Forsén, Rikard
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Coherency strain engineered decomposition of unstable multilayer alloys for improved thermal stability2013Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 114, nr 24, s. 244303-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A concept to improve hardness and thermal stability of unstable multilayer alloys is presented based on control of the coherency strain such that the driving force for decomposition is favorably altered. Cathodic arc evaporated cubic TiCrAlN/Ti 1−x Cr x N multilayer coatings are used as demonstrators. Upon annealing, the coatings undergo spinodal decomposition into nanometer-sized coherent Ti- and Al-rich cubic domains which is affected by the coherency strain. In addition, the growth of the domains is restricted by the surrounding TiCrN layer compared to a non-layered TiCrAlN coating which together results in an improved thermal stability of the cubic structure. A significant hardness increase is seen during decomposition for the case with high coherency strain while a low coherency strain results in a hardness decrease for high annealing temperatures. The metal diffusion paths during the domain coarsening are affected by strain which in turn is controlled by the Cr-content (x) in the Ti 1−x Cr x N layers. For x = 0 the diffusion occurs both parallel and perpendicular to the growth direction but for x > =0.9 the diffusion occurs predominantly parallel to the growth direction. Altogether this study shows a structural tool to alter and fine-tune high temperature properties of multicomponent materials.

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  • 17.
    Forsén, Rikard
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Johansson, M P.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Effects of Ti alloying of AlCrN coatings on thermal stability and oxidation resistance2013Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 534, s. 394-402Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quaternary cubic (TixCr1 − xAl~ 0.60)1 N1 coatings with 0 < x < 0.33 have been grown using reactive cathodic arc evaporation. When adding Ti the hardness was retained after annealing up to 1100 °C which is a dramatic improvement compared to CrAlN coatings. The coatings showed an age hardening process caused by spinodal decomposition into coherent TiCr- and Al-rich cubic TiCrAlN domains and the formation of hexagonal AlN precipitates and cubic TiCrN domains in the vicinity of the grain boundaries. The improved hardness was attributed to the stabilization of the cubic structure suppressing the formation and growth of hexagonal AlN. Furthermore, the presence of Ti atoms generated incoherent nanometer-sized crystallites within the hexagonal AlN precipitates disrupting the hexagonal lattice during the coarsening process.

    The addition of Ti promoted the formation of a TiO2 layer over Al2O3 resulting in a lower oxidation resistance. However, by tuning the composition it is possible to design coatings to have both good oxidation resistance and good high temperature mechanical stability.

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  • 18.
    Forsén, Rikard
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Johansson, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Decomposition and phase transformation in TiCrAlN thin coatings2012Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 30, nr 6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Phase transformations and mechanisms that yield enhanced high temperature mechanical properties of metastable solid solutions of cubic (c)-(TixCryAlz)N coatings are discussed in this paper. Coatings grown by reactive arc evaporation technique with metal composition range y<17 at. % and 45<z<62 at. % are studied and compared with the parent TiAlN material system. The coatings exhibit age hardening up to 1000 ºC which is higher compared to what is observed for TiAlN. In addition, the coatings show a less pronounced hardness decrease when hexagonal (h)-AlN is formed compared to TiAlN. The improved thermal stability is discussed in terms of a lowered coherency stress and a lowered enthalpy of mixing due to the addition of Cr, which results in improved functionality in the working temperature range of 850-1000 ºC of for example cutting tools. Upon annealing up to 1400 ºC the coatings decompose into c-TiN, bcc-Cr and h-AlN. The decomposition takes place via several intermediate phases, c-CrAlN, c-TiCrN and hexagonal (β)-Cr2N. The microstructure  evolution investigated at different stages of spinodal decomposition and phase transformation is correlated to the thermal response and mechanical hardness of the coatings.

  • 19.
    Forsén, Rikard
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Johansson, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Improved mechanical properties in oxidation resistant AlCrN coatings through Ti additionManuskript (preprint) (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Quaternary cubic (c)-(TixCryAl~0.60)1N1 coatings with different x to y ratios have been grown using reactive cathodic arc evaporation. Results show that by adding Ti the high temperature mechanical properties are drastically improved with a retained hardness up to 1100 ºC. The coatings show an age hardening process caused by the formation of hexagonal (h)-AlN and cubic (c)-TiCrN precipitates surrounded by a TiCrAlN host matrix. The improved properties are discussed in terms of kinetics where the addition of Ti delays and suppresses the growth the h-AlN phase. The Ti atoms also generate incoherent crystallites within the h-AlN domains disrupting the hexagonal lattice during the coarsening process. Altogether the result is that the detrimental effects that are normally associated with the hexagonal phase are shifted to higher temperatures.

    The oxidation resistance is also investigated with different amount of Ti addition. The addition of Ti promotes the formation of a TiO2 oxide layer over Al2O3 resulting in a lower oxidation resistance. However, by tuning the composition it is possible to generate coatings having both high oxidation resistance and excellent high temperature mechanical properties.

  • 20.
    Forsén, Rikard
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Schramm, I. C.
    Functional Materials, Department Materials Science, Saarland University, Saarbrücken, Germany.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per O Å
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Mücklich, F.
    Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Nanostructuring and coherency strain in multicomponent hard coatings2014Ingår i: APL MATERIALS, ISSN 2166-532X, Vol. 2, nr 11, s. 116104-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lattice resolved and quantitative compositional characterizations of the microstructure in TiCrAlN wear resistant coatings emerging at elevated temperatures are performed to address the spinodal decomposition into nanometer-sized coherent cubic TiCr- and Al-rich domains. The domains coarsen during annealing and at 1100 ºC, the Al-rich domains include a metastable cubic Al(Cr)N phase containing 9 at.% Cr and a stable hexagonal AlN phase containing less than 1 at.% Cr. The cubic and the hexagonal phases form strained semi-coherent interfaces with each other.

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  • 21.
    Forsén, Rikard
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Syed, Muhammad Bilal
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Alloying as a tool for structure and thermal stability engineering of hard coatings2014Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    A large range of (ZrxAly Cr(100-x-y))1N1 coatings have been deposited using cathodic arc evaporation and annealed at temperatures up to 1100 ºC. The coatings can be divided into three different characteristic categories based on their structure, thermal stability and hardness.

    The first category of coatings, (Al < ~30 % and ~40 % < Zr), are stable cubic solid solutions up to 1100 ºC. The hardness decreases upon annealing because of defect annihilation.

    In the second category, (40 % < Al < 60 % and Zr < 15 %), the coatings decompose into ZrCr- and Al-rich nanometer-sized domains when annealed, which results in a hardness increase.

    In the third category (~67 % < Al), the microstructure contain a mixture of 1-2 nanometer-sized nano-crystalline hexagonal (AlN) and cubic (ZrCrN) phases. These coatings have a significantly lower hardness in the as deposited state but upon annealing the hardness increases significantly.

  • 22. Beställ onlineKöp publikationen >>
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Growth and Nano-structural Studies of Metallic Multilayer for X-ray Mirrors2005Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    A part of the Ph.D. project focused on growth and characterization of metal multilayers is presented in this licentiate thesis. The main interest in carrying out this research is to develop highly reflective normal-incidence condenser mirrors for soft X-ray microscopy studies in the water window (λ=2.4-4.2 nm) wavelength regime.

    Transition metals like Sc, Ti V, etc. have been considered because of the presence of their 2p-absorption edges within the water window. An anomalous dispersion at absorption edges has been utilized to get enhanced reflectance of soft X-rays. Since a single surface exhibits a very poor X-ray reflectivity, Cr/Sc, Cr/Ti, and Ni/V multilayers were grown in order to coherently add many reflections from several interfaces. The selection of Cr and Ni, as spacer layer, was made on the basis of their X-ray optical contrasts with the above-mentioned transition metals. The multilayer design, i.e., the individual layer thicknesses and the total number of bilayers, directly influences the resultant reflectance and careful determination was therefore made with the aid of computer simulations.

    All multilayers were grown on chemically cleaned Si substrates by ion-assisted dual target magnetron sputtering under high vacuum (~10-7 Torr) conditions. The effect of low and high ion-flux bombardment of low energy (<50 eV) Ar ions, on growing surfaces was studied for all material systems. Furthermore, a two-stage deposition of each individual layer with modulated ion-energies was applied in order to obtain smooth and abrupt interfaces with as small intermixing as possible. Ion-surface interactions were also theoretically considered for estimating an appropriate ion-flux and ion-energy range desired for sufficient ad-atom mobilities.

    X-ray reflectivity and transmission electron microscopy have been the main probes for multilayer characterization in this work. For the Cr/Ti multilayer designed for normal incidence and grown with optimized two-stage ion-energy modulation, a peak reflectance of 2.1% was achieved at the Ti-2p absorption edge (λ=2.74 nm). For a multilayer mirror designed for the Brewster angle a maximum reflectance of 4.3% was accomplished. These measurements were made at the synchrotron radiation source BESSY in Berlin. Specular reflectivity and diffuse scattering scans were utilized for quantitative and qualitative analysis of the vertical and lateral structure of the multilayers. At-wavelength measurements of a series of Cr/Ti multilayers revealed the accumulation of roughness with increasing number of bilayers (N>100) for this material system. Hard X-ray reflectivity and diffractometry were used for quality checks of the multilayers for rapid feedback to the deposition. In-situ annealing using hard X-ray reflectivity was also performed to assess the thermal stability of Cr/Ti multilayers. It was found that probably due to a strong thermal diffusion the degradation of multilayers (with bilayer period of 1.37 nm) in this material system occurs just above the growth temperature (~40°C). The accumulation of a low spatial frequency "waviness" with increasing number of layers in Cr/Ti multilayers was investigated by transmission electron microscopy. The influence of process conditions on multilayer structure with different periodicities was investigated by TEM analyses of a series of three samples for each of the above-mentioned material system. The Cr/Sc multilayers have shown the most flat and abrupt interface structure without any significant roughness evolution when grown with optimum process parameters.

    Delarbeten
    1. Interface engineered ultra-short period Cr/Ti multilayers as high reflectance mirrors and polarizers for soft X-rays of lambda=2.74 nm wavelength
    Öppna denna publikation i ny flik eller fönster >>Interface engineered ultra-short period Cr/Ti multilayers as high reflectance mirrors and polarizers for soft X-rays of lambda=2.74 nm wavelength
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    2006 (Engelska)Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 45, nr 1, s. 137-143Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Cr-Ti multilayers with ultrashort periods of 1.39-2.04 nm have been grown for the first time as highly reflective, soft-x-ray multilayer, near-normal incidence mirrors for transition radiation and Cherenkov radiation x-ray sources based on the Ti-2p absorption edge at E = 452eV (lambda = 2.74 nm). Hard, as well as soft, x-ay reflectivity and transmission electron microscopy were used to characterize the nanostructure of the mirrors. To achieve minimal accumulated roughness, improved interface flatness, and to avoid intermixing at the interfaces, each individual layer was engineered by use of a two-stage ion assistance process during magnetron sputter deposition: The first 0.3 nm of each Ti and Cr layer was grown without ion assistance, and the remaining 0.39-0.72 nm of the layers were grown with high ion-neutral flux ratios Phi˙(PhiTi = 3.3, PhiCr = 2.2) and a low energy Eion (ETi = 23.7 and ECr = 21.2), ion assistance. A maximum soft-x-ray reflectivity of R = 2.1% at near-normal incidence (~78.8°) was achieved for a multilayer mirror containing 100 bilayers with a modulation period of 1.379 nm and a layer thickness ratio of Gamma = 0.5. For a polarizing multilayer mirror with 150 bilayers designed for operation at the Brewster angle, 45°, an extinction ratio, Rs/Rp, of 266 was achieved with an absolute reflectivity of R = 4.3%.

    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-13066 (URN)10.1364/AO.45.000137 (DOI)
    Tillgänglig från: 2008-05-06 Skapad: 2008-05-06 Senast uppdaterad: 2020-03-19
    2. Effects of ion-assisted growth on the layer definition in Cr/Sc multilayers
    Öppna denna publikation i ny flik eller fönster >>Effects of ion-assisted growth on the layer definition in Cr/Sc multilayers
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    2008 (Engelska)Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 516, nr 6, s. 982-990Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Nano-structural evolution of layer morphology and interfacial roughness in Cr/Sc metal multilayers grown with ion assistance during magnetron sputter deposition has been investigated by high resolution transmission electron microscopy and hard X-ray reflectivity. Calculations based on a binary collision model predict an ion-assisted growth window for optimized Cr/Sc multilayer interface sharpness, within the ion energy range of 21 eV to 37 eV and an ion flux of 10 ions per deposited atom. Multilayers with nominal modulation periods in the range of 1.6 nm to 10.2 nm, grown with these conditions, exhibit a well-defined layer structure with an improved flattening and abruptness of the interfaces. It is shown that multilayers with a modulation period smaller than 3.4 nm have clear benefit from the reduced intermixing obtained by utilizing a two-stage ion energy modulation for each individual layer. The amorphization of Sc and Cr layers, below certain thicknesses, is found to be independent of the low energy ion-assistance. It is also shown that the Cr/Sc multilayers, containing periods less than 2 nm are ‘self healing’ i.e. they re-gain abrupt interfaces and flat layers after morphological disturbances during ion assisted growth. In comparison, multilayers grown without ion-assistance exhibited severe roughness and layer distortions.

    Ort, förlag, år, upplaga, sidor
    Institutionen för fysik, kemi och biologi, 2008
    Nyckelord
    Multilayers, X-ray mirrors, Ion assistance, Magnetron sputtering, Cr/Sc multilayers, Interface engineering, Optical coatings, Surface roughness
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-11487 (URN)10.1016/j.tsf.2007.06.108 (DOI)
    Anmärkning
    Original publication: N. Ghafoor, F. Eriksson, P.O.Å. Persson, L. Hultman and J. Birch, Effects of ion-assisted growth on the layer definition in Cr/Sc multilayers, 2008, Thin Solid Films, (516), 6, 982-990. http://dx.doi.org/10.1016/j.tsf.2007.06.108. Copyright: Elsevier B.V., http://www.elsevier.com/Tillgänglig från: 2008-04-04 Skapad: 2008-04-04 Senast uppdaterad: 2020-03-19
    3. Atomic scale interface engineering by modulated ion-assisted deposition applied to soft x-ray multilayer optics
    Öppna denna publikation i ny flik eller fönster >>Atomic scale interface engineering by modulated ion-assisted deposition applied to soft x-ray multilayer optics
    Visa övriga...
    2008 (Engelska)Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 47, nr 23, s. 4196-4204Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Cr/Sc and Ni/V multilayers, intended as normal incidence soft x-ray mirrors and Brewster angle polarizers, have been synthesized by employing a novel modulated low-energy and high-flux ion assistance as a means of engineering the interfaces between the subnanometer layers on an atomic scale during magnetron sputter deposition. To reduce both roughness and intermixing, the ion energy was modulated within each layer. The flat and abrupt interfaces yielded soft x-ray mirrors with near-normal incidence reflectances of R = 20.7% at the Sc 2p absorption edge and R = 2.7% at the V 2p absorption edge. Multilayers optimized for the Brewster angle showed a reflectance of R = 26.7% and an extinction ratio of Rs/Rp=5450 for Cr/Sc and R = 10% and Rs/Rp=4190 for Ni/V. Transmission electron microscopy investigations showed an amorphous Cr/Sc structure with an accumulating high spatial frequency roughness. For Ni/V the initial growth mode is amorphous and then turns crystalline after ~1/3 of the total thickness, with an accumulating low spatial frequency roughness as a consequence. Elastic recoil detection analyses showed that N was the major impurity in both Cr/Sc and Ni/V with concentrations of 15 at. % and 9 at. %, respectively, but also O (3 at. % and 1.3 at. %) and C (0.5 at. % and 1.9 at. %) were present. Simulations of the possible normal incidence reflective properties in the soft x-ray range of 100-600 eV are given, predicting that reflectivities of more than 31% for Cr/Sc and 5.8% for Ni/V can be achieved if better control of the impurities and the deposition process is employed. The simulations also show that Cr/Sc is a good candidate for mirrors for the photon energies between the absorption edges of B (E = 188 eV) and Sc (E = 398.8 eV).

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-13060 (URN)10.1364/AO.47.004196 (DOI)
    Tillgänglig från: 2008-05-06 Skapad: 2008-05-06 Senast uppdaterad: 2020-03-19
    Ladda ner fulltext (pdf)
    FULLTEXT01
    Ladda ner (pdf)
    COVER01
  • 23. Beställ onlineKöp publikationen >>
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Materials Science of Multilayer X-ray Mirrors2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Denna avhandling behandlar syntes, analys, och materialvetenskap rörande så kallade multilagerspeglar för mjuk röntgenstrålning. Speglarna är lämpade som optiska komponenter för instrument såsom röntgenmikroskop i våglängdsområdet 2,4 nm till 4,4 nm, även kallat vattenfönstret.

    Tack vare de senaste decenniernas stora teknologiska och vetenskapliga framsteg i att framställa mycket intensiva källor för mjuk röntgenstrålning, såsom tex synkrotronljuskällor, frielektronlasrar, och plasmagenererade källor, är det nu tänkbart att utnyttja denna strålning till nya tillämpningar som tidigare inte varit möjliga. Några exempel är; röntgenmikroskopi av biologiska preparat med upplösning ca 1/100 av det som är möjligt med synligt ljus, fotolitografi av

    Det finns flera stora utmaningar för att lyckas tillverka multilagerspeglar. Först och främst måste man hitta materialkombinationer som ger upphov till reflektion i mellanytorna mellan materialen men som inte samtidigt absorberar all röntgenstrålning. Dessutom måste materialen gå att belägga på varandra i flera hundra tunna lager, vart och ett endast ca 1 nanometer tjockt, med en ytojämnhet om endast några tiondels nanometer. Den absoluta tjockleks precision i varje

    I det här arbetet har fyra olika typer av multilagerbeläggningar undersökts: krom/titan (Cr/Ti), krom/skandium (Cr/Sc), nickel/vanadin (Ni/V) samt kromnitrid/skandiumnitrid (CrN/ScN). Materialvalen har baserats på teoretiska beräkningar som visat att dessa materialsystem genererar mycket god reflektans i vattenfönstret. Varje kombination av metaller är optimal för en specifik våglängd och de individuella lagertjocklekarna måste optimeras teoretiskt för varje enskilt

    För Cr/Sc multilager har vi visat att lagren som beläggs har en oordnad, så kallad amorf, struktur mellan metallatomerna som har sitt ursprung i att multilagrets totala energi kan sänkas om mellanytor mellan kristallint Cr och kristallint Sc kan undvikas.

    Studier av effekterna av kväveupptag hos Cr/Sc multilagerspeglar under sputtringsprocessen har lett till ökad förståelse av materialsystemet. Till exempel har vi visat att kvävet framförallt binder till de inre regionerna av Sc och inte så mycket till Cr-lagren eller i mellanytorna. Med kväve i strukturen har vi gjort speglar som tål höga temperaturer, vilket är av stor betydelse för tillämpningar baserade högintensiva ljuskällor. Så kallade supergitter, dvs multilager

    Delarbeten
    1. Atomic scale interface engineering by modulated ion-assisted deposition applied to soft x-ray multilayer optics
    Öppna denna publikation i ny flik eller fönster >>Atomic scale interface engineering by modulated ion-assisted deposition applied to soft x-ray multilayer optics
    Visa övriga...
    2008 (Engelska)Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 47, nr 23, s. 4196-4204Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Cr/Sc and Ni/V multilayers, intended as normal incidence soft x-ray mirrors and Brewster angle polarizers, have been synthesized by employing a novel modulated low-energy and high-flux ion assistance as a means of engineering the interfaces between the subnanometer layers on an atomic scale during magnetron sputter deposition. To reduce both roughness and intermixing, the ion energy was modulated within each layer. The flat and abrupt interfaces yielded soft x-ray mirrors with near-normal incidence reflectances of R = 20.7% at the Sc 2p absorption edge and R = 2.7% at the V 2p absorption edge. Multilayers optimized for the Brewster angle showed a reflectance of R = 26.7% and an extinction ratio of Rs/Rp=5450 for Cr/Sc and R = 10% and Rs/Rp=4190 for Ni/V. Transmission electron microscopy investigations showed an amorphous Cr/Sc structure with an accumulating high spatial frequency roughness. For Ni/V the initial growth mode is amorphous and then turns crystalline after ~1/3 of the total thickness, with an accumulating low spatial frequency roughness as a consequence. Elastic recoil detection analyses showed that N was the major impurity in both Cr/Sc and Ni/V with concentrations of 15 at. % and 9 at. %, respectively, but also O (3 at. % and 1.3 at. %) and C (0.5 at. % and 1.9 at. %) were present. Simulations of the possible normal incidence reflective properties in the soft x-ray range of 100-600 eV are given, predicting that reflectivities of more than 31% for Cr/Sc and 5.8% for Ni/V can be achieved if better control of the impurities and the deposition process is employed. The simulations also show that Cr/Sc is a good candidate for mirrors for the photon energies between the absorption edges of B (E = 188 eV) and Sc (E = 398.8 eV).

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-13060 (URN)10.1364/AO.47.004196 (DOI)
    Tillgänglig från: 2008-05-06 Skapad: 2008-05-06 Senast uppdaterad: 2020-03-19
    2. Effects of ion-assisted growth on the layer definition in Cr/Sc multilayers
    Öppna denna publikation i ny flik eller fönster >>Effects of ion-assisted growth on the layer definition in Cr/Sc multilayers
    Visa övriga...
    2008 (Engelska)Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 516, nr 6, s. 982-990Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Nano-structural evolution of layer morphology and interfacial roughness in Cr/Sc metal multilayers grown with ion assistance during magnetron sputter deposition has been investigated by high resolution transmission electron microscopy and hard X-ray reflectivity. Calculations based on a binary collision model predict an ion-assisted growth window for optimized Cr/Sc multilayer interface sharpness, within the ion energy range of 21 eV to 37 eV and an ion flux of 10 ions per deposited atom. Multilayers with nominal modulation periods in the range of 1.6 nm to 10.2 nm, grown with these conditions, exhibit a well-defined layer structure with an improved flattening and abruptness of the interfaces. It is shown that multilayers with a modulation period smaller than 3.4 nm have clear benefit from the reduced intermixing obtained by utilizing a two-stage ion energy modulation for each individual layer. The amorphization of Sc and Cr layers, below certain thicknesses, is found to be independent of the low energy ion-assistance. It is also shown that the Cr/Sc multilayers, containing periods less than 2 nm are ‘self healing’ i.e. they re-gain abrupt interfaces and flat layers after morphological disturbances during ion assisted growth. In comparison, multilayers grown without ion-assistance exhibited severe roughness and layer distortions.

    Ort, förlag, år, upplaga, sidor
    Institutionen för fysik, kemi och biologi, 2008
    Nyckelord
    Multilayers, X-ray mirrors, Ion assistance, Magnetron sputtering, Cr/Sc multilayers, Interface engineering, Optical coatings, Surface roughness
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-11487 (URN)10.1016/j.tsf.2007.06.108 (DOI)
    Anmärkning
    Original publication: N. Ghafoor, F. Eriksson, P.O.Å. Persson, L. Hultman and J. Birch, Effects of ion-assisted growth on the layer definition in Cr/Sc multilayers, 2008, Thin Solid Films, (516), 6, 982-990. http://dx.doi.org/10.1016/j.tsf.2007.06.108. Copyright: Elsevier B.V., http://www.elsevier.com/Tillgänglig från: 2008-04-04 Skapad: 2008-04-04 Senast uppdaterad: 2020-03-19
    3. Incorporation of nitrogen in Cr/Sc multilayers giving improved soft x-ray reectivity
    Öppna denna publikation i ny flik eller fönster >>Incorporation of nitrogen in Cr/Sc multilayers giving improved soft x-ray reectivity
    Visa övriga...
    2008 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, nr 9, s. 091913-Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Soft x-ray reflectivity (SXR) of Cr/Sc multilayer with bilayer thickness of =1.56  nm was increased by 100% by an intentional introduction of nitrogen during magnetron sputtering. Multilayers deposited at background pressures of 2×10−6 Torr exhibited amorphous layers with flat interfaces. At 2×10−5 Torr, understoichiometric CrNx/ScNy multilayer with a nitrogen content of ~34  at.  % was formed. CrNx/ScNy multilayer comprising of only 100 periods exhibited a SXR of 11.5%. X-ray and electron microscopy analyses showed that the improvement in performance is a result of reduced interfacial diffusion yielding interface widths of 0.29  nm. The CrNx/ScNy multilayer exhibited thermal stability up to >380  °C.

    Nyckelord
    chemical interdiffusion, chromium, doping, electron microscopy, multilayers, nitrogen, scandium, sputter deposition, thermal stability, X-ray microscopy, X-ray reflection
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-13062 (URN)10.1063/1.2857459 (DOI)
    Tillgänglig från: 2008-05-06 Skapad: 2008-05-06 Senast uppdaterad: 2020-03-19
    4. Effects of O and N impurities on the nanostructural evolution during growth of Cr/Sc multilayers
    Öppna denna publikation i ny flik eller fönster >>Effects of O and N impurities on the nanostructural evolution during growth of Cr/Sc multilayers
    Visa övriga...
    2009 (Engelska)Ingår i: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 24, nr 1, s. 79-95Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Transition metal multilayers are prime candidates for high reflectivity soft x-ray multilayer mirrors. In particular, Cr/Sc multilayers in the amorphous state have proven to give the highest reflectivity in the water window. We have investigated the influence of impurities N and O as residual gas elements on the growth, structure, and optical performance of Cr/Sc multilayers deposited in high vacuum conditions by a dual cathode direct current magnetron sputter deposition. Multilayer structures with the modulation periods in the range of 0.9–4.5 nm and Cr layer to bilayer thickness ratios in the range of 0.17–0.83 were deposited with an intentionally raised base pressure (pB), ranging from 2 × 10-7 to 2 × 10-5 Torr. Compositional depth profiles were obtained by elastic recoil detection analysis and Rutherford backscattering spectroscopy, while the structural investigations of the multilayers were carried out using hard x-ray reflectivity and transmission electron microscopy. By investigating stacked multilayers, i.e., several multilayers with different designs of the modulation periods, stacked on top of each other in the samples, we have been able to conclude that both N and O are incorporated preferentially in the interior of the Sc layers. At pB = 2 × 10-6 Torr, typically <3 at.% of N and <1.5 at.% of O was found, which did not influence the amorphous nanostructure of the layers. Multilayers deposited with a high pB ~2 × 10-5 Torr, a N content as high as ~37 at.% was measured by elastic recoil detection analysis. These multilayers mainly consist of understoichiometric face-centered cubic CrN x /ScN y nanocrystalline layers, which could be grown as thin at 0.3 nm and is explained by a stabilizing effect on the ScN y layers during growth. It is also shown that by adding a background pressure of as little as 5 × 10-6 Torr of pure N2 the soft x-ray reflectivity (? = 3.11 nm) can be enhanced by more than 100% by N incorporation into the multilayer structures, whereas pure O2 at the same background pressure had no effect.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-13063 (URN)10.1557/JMR.2009.0004 (DOI)
    Tillgänglig från: 2008-05-06 Skapad: 2008-05-06 Senast uppdaterad: 2020-03-19
    5. Reflectivity and structural evolution of Cr/Sc and nitrogen containing Cr/Sc multilayers during thermal annealing
    Öppna denna publikation i ny flik eller fönster >>Reflectivity and structural evolution of Cr/Sc and nitrogen containing Cr/Sc multilayers during thermal annealing
    2008 (Engelska)Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 104, nr 6, s. 063516-Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    It is shown that the thermal stability in vacuum of Cr/Sc multilayer thin films used as reflective optical components in soft x-ray instrumentation has substantial dependence on incorporation of N. The thermal stability is increased by incorporating 34 at.% of N in Cr/Sc multilayers. A pure Cr/Sc multilayer x-ray mirror starts a continuous degradation already at ~100 °C with a complete destruction of the multilayer at 500 °C. The resulting structure is a mixture of Cr and Sc nanocrystallites. The degradation can be described by linear diffusion theory and is suggested to be due to the formation of uniformly distributed phase-separated nanocrystallites followed by an Ostwald ripening process with an apparent activation energy of 0.5 eV. At the multilayer-substrate interface, a 7 nm thin Sc-Si layer is formed which effectively hinders indiffusion of Si and outdiffusion of Cr and Sc. A nitrided multilayer, initially consisting of crystalline fcc CrNx and fcc ScNy layers (x and y<1), is observed to improve in structural quality up to ~250 °C where it is stable for more than 12 h. At ~330 °C, the multilayer separates into regions with two multilayer periods, differing by less than 0.04 nm, which are stable at 420 °C over an extended period of time >40 h. It is proposed that the separation into the different multilayer periods is a consequence of redistribution of N within the Cr layers. Sc is observed to be stabilized in the ScN layers, which, in turn, inhibit the formation of a Sc-Si barrier layer at the substrate leading to a strong exchange of Si and Cr across the film substrate. This leads to a Cr-Si/ScN layered structure close to the substrate and chromium silicide crystallites inside the substrate. Close to the top of the multilayer, a CrN/ScN multilayer appears to be retained.

    Nyckelord
    annealing, chromium, multilayers, reflectivity, scandium, thermal stability, thin films, X-ray optics, X-ray reflection
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-13064 (URN)10.1063/1.2980051 (DOI)
    Tillgänglig från: 2008-05-06 Skapad: 2008-05-06 Senast uppdaterad: 2020-03-19
    6. Single crystal CrN/ScN superlattice soft X-ray mirrors: epitaxial growth, structure, and properties
    Öppna denna publikation i ny flik eller fönster >>Single crystal CrN/ScN superlattice soft X-ray mirrors: epitaxial growth, structure, and properties
    Visa övriga...
    2006 (Engelska)Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 514, nr 1-2, s. 10-19Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Single crystal CrN/ScN superlattice films with modulation periods of 1.64 nm were grown on MgO(001) substrates. By utilizing a magnetically enhanced plasma in the vicinity of the substrate and a negative substrate bias, ion/metal nitride flux ratios of 45 and 144 were achieved during deposition of CrN and ScN, respectively. The effects of ion energies in the range [16–58 eV] and substrate temperatures in the range [535–853 °C] on the composition, interface width, crystal quality, and microstructure evolution were investigated using elastic recoil detection analysis, hard X-ray reflectivity, X-ray diffraction, and transmission electron microscopy (TEM). Minimal interface widths of 0.2 nm = 1/2 nitride unit cell were achieved at a growth temperature of 735 °C and ion energies of 24 and 28 eV for CrN and ScN, respectively. Under these conditions, also an optimum in the crystal quality was observed for near stoichiometric composition of CrN and ScN. TEM confirmed a cube-on-cube epitaxial relationship for the system with CrN(001)ScN(001)MgO(001) and CrN[100]ScN[100]MgO[100]. Also, the layers were coherently strained to each other with no misfit dislocations, threading dislocations, surface cusps, voids or gas bubbles present. Higher ion energies or lower deposition temperatures gave over-stoichiometric films with poor superlattice modulation while higher growth temperatures yielded a decreased crystal quality, due to loss of N. As-deposited superlattices with only 61 periods exhibited an absolute soft X-ray reflectance of 6.95% at an energy of 398.8 eV (Sc 2p-absorption edge) which is comparable to the performance of Cr/Sc. The compositional modulation and phase structure was stable during extended annealing at 850 °C, which is the highest thermal stability for an X-ray multilayer mirror. It is concluded that the ScN layers serve as effective diffusion barriers to hinder decomposition of the CrN layers and stabilize the pseudomorphic superlattice structure. Nanoindentation experiments showed that the hardness of the CrN/ScN superlattice films was 19 GPa.

    Nyckelord
    CrN, ScN, Superlattice, X-ray mirrors, Reactive magnetron sputtering
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-13065 (URN)10.1016/j.tsf.2006.02.011 (DOI)
    Tillgänglig från: 2008-05-06 Skapad: 2008-05-06 Senast uppdaterad: 2020-03-19
    7. Interface engineered ultra-short period Cr/Ti multilayers as high reflectance mirrors and polarizers for soft X-rays of lambda=2.74 nm wavelength
    Öppna denna publikation i ny flik eller fönster >>Interface engineered ultra-short period Cr/Ti multilayers as high reflectance mirrors and polarizers for soft X-rays of lambda=2.74 nm wavelength
    Visa övriga...
    2006 (Engelska)Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 45, nr 1, s. 137-143Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Cr-Ti multilayers with ultrashort periods of 1.39-2.04 nm have been grown for the first time as highly reflective, soft-x-ray multilayer, near-normal incidence mirrors for transition radiation and Cherenkov radiation x-ray sources based on the Ti-2p absorption edge at E = 452eV (lambda = 2.74 nm). Hard, as well as soft, x-ay reflectivity and transmission electron microscopy were used to characterize the nanostructure of the mirrors. To achieve minimal accumulated roughness, improved interface flatness, and to avoid intermixing at the interfaces, each individual layer was engineered by use of a two-stage ion assistance process during magnetron sputter deposition: The first 0.3 nm of each Ti and Cr layer was grown without ion assistance, and the remaining 0.39-0.72 nm of the layers were grown with high ion-neutral flux ratios Phi˙(PhiTi = 3.3, PhiCr = 2.2) and a low energy Eion (ETi = 23.7 and ECr = 21.2), ion assistance. A maximum soft-x-ray reflectivity of R = 2.1% at near-normal incidence (~78.8°) was achieved for a multilayer mirror containing 100 bilayers with a modulation period of 1.379 nm and a layer thickness ratio of Gamma = 0.5. For a polarizing multilayer mirror with 150 bilayers designed for operation at the Brewster angle, 45°, an extinction ratio, Rs/Rp, of 266 was achieved with an absolute reflectivity of R = 4.3%.

    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-13066 (URN)10.1364/AO.45.000137 (DOI)
    Tillgänglig från: 2008-05-06 Skapad: 2008-05-06 Senast uppdaterad: 2020-03-19
    Ladda ner fulltext (pdf)
    FULLTEXT01
    Ladda ner (pdf)
    COVER01
  • 24.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Andrew, Aquila
    SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California, USA.
    Gullikson, Eric
    Center for X-Ray Optics, Lawrence Berkeley National Lab, Berkeley, California, USA.
    Franz, Schäfers
    Institute for Nanometre Optics and Technology Helmholtz Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, Berlin, Germany.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Impact of B4C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors2017Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, nr 15, s. 18274-18287Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of B4C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics is investigated. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization near Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added.

    Ladda ner fulltext (pdf)
    fulltext
  • 25.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Gullikson, Eric M
    Lawrence Berkeley Laboratory.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Incorporation of nitrogen in Cr/Sc multilayers giving improved soft x-ray reectivity2008Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, nr 9, s. 091913-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Soft x-ray reflectivity (SXR) of Cr/Sc multilayer with bilayer thickness of =1.56  nm was increased by 100% by an intentional introduction of nitrogen during magnetron sputtering. Multilayers deposited at background pressures of 2×10−6 Torr exhibited amorphous layers with flat interfaces. At 2×10−5 Torr, understoichiometric CrNx/ScNy multilayer with a nitrogen content of ~34  at.  % was formed. CrNx/ScNy multilayer comprising of only 100 periods exhibited a SXR of 11.5%. X-ray and electron microscopy analyses showed that the improvement in performance is a result of reduced interfacial diffusion yielding interface widths of 0.29  nm. The CrNx/ScNy multilayer exhibited thermal stability up to >380  °C.

  • 26.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Mikhaylushkin, Arkady
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Gullikson, Eric M.
    Beckers, Manfred
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Kressing, U.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Effects of O and N impurities on the nanostructural evolution during growth of Cr/Sc multilayers2009Ingår i: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 24, nr 1, s. 79-95Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transition metal multilayers are prime candidates for high reflectivity soft x-ray multilayer mirrors. In particular, Cr/Sc multilayers in the amorphous state have proven to give the highest reflectivity in the water window. We have investigated the influence of impurities N and O as residual gas elements on the growth, structure, and optical performance of Cr/Sc multilayers deposited in high vacuum conditions by a dual cathode direct current magnetron sputter deposition. Multilayer structures with the modulation periods in the range of 0.9–4.5 nm and Cr layer to bilayer thickness ratios in the range of 0.17–0.83 were deposited with an intentionally raised base pressure (pB), ranging from 2 × 10-7 to 2 × 10-5 Torr. Compositional depth profiles were obtained by elastic recoil detection analysis and Rutherford backscattering spectroscopy, while the structural investigations of the multilayers were carried out using hard x-ray reflectivity and transmission electron microscopy. By investigating stacked multilayers, i.e., several multilayers with different designs of the modulation periods, stacked on top of each other in the samples, we have been able to conclude that both N and O are incorporated preferentially in the interior of the Sc layers. At pB = 2 × 10-6 Torr, typically <3 at.% of N and <1.5 at.% of O was found, which did not influence the amorphous nanostructure of the layers. Multilayers deposited with a high pB ~2 × 10-5 Torr, a N content as high as ~37 at.% was measured by elastic recoil detection analysis. These multilayers mainly consist of understoichiometric face-centered cubic CrN x /ScN y nanocrystalline layers, which could be grown as thin at 0.3 nm and is explained by a stabilizing effect on the ScN y layers during growth. It is also shown that by adding a background pressure of as little as 5 × 10-6 Torr of pure N2 the soft x-ray reflectivity (? = 3.11 nm) can be enhanced by more than 100% by N incorporation into the multilayer structures, whereas pure O2 at the same background pressure had no effect.

  • 27.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per O.Å
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Effects of ion-assisted growth on the layer definition in Cr/Sc multilayers2008Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 516, nr 6, s. 982-990Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nano-structural evolution of layer morphology and interfacial roughness in Cr/Sc metal multilayers grown with ion assistance during magnetron sputter deposition has been investigated by high resolution transmission electron microscopy and hard X-ray reflectivity. Calculations based on a binary collision model predict an ion-assisted growth window for optimized Cr/Sc multilayer interface sharpness, within the ion energy range of 21 eV to 37 eV and an ion flux of 10 ions per deposited atom. Multilayers with nominal modulation periods in the range of 1.6 nm to 10.2 nm, grown with these conditions, exhibit a well-defined layer structure with an improved flattening and abruptness of the interfaces. It is shown that multilayers with a modulation period smaller than 3.4 nm have clear benefit from the reduced intermixing obtained by utilizing a two-stage ion energy modulation for each individual layer. The amorphization of Sc and Cr layers, below certain thicknesses, is found to be independent of the low energy ion-assistance. It is also shown that the Cr/Sc multilayers, containing periods less than 2 nm are ‘self healing’ i.e. they re-gain abrupt interfaces and flat layers after morphological disturbances during ion assisted growth. In comparison, multilayers grown without ion-assistance exhibited severe roughness and layer distortions.

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  • 28.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Johnson, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Self-organized Labyrinthine Nanostructure in Zr0.64Al0.36N Thin FilmsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Self-organization of functional ceramics on the nanometer scale drives scientific and technological research in such diverse fields as cutting tools and light-emitting diodes. A classic example is spinodal decomposition in TiAlN thin films, which yields intricate nanostructures from the isostructural decomposition into cubic-structrure (c) AlN and TiN domains, resulting in age hardening [1]. Here, we explore the ZrN-AlN system, which has one of the largest positive enthalpies of mixing among the systems combining a transition metal nitride and a wide-band gap nitride [2]. Interestingly, an original nanolabyrinthine structure evolves during thin film synthesis of Zr0.64Al0.36N. It consists of the non-isostructural phases c-ZrN and wurtzite-AlN with standing {110}‖{112̄0} planes.The selforganization in this system is discussed in terms of a competition between interfacial and surface elastic energy, which produces a structure with a well-defined length scale. This effective nanostructural design yields films with hardnesses of 36 GPa, 44 % higher than comparable ZrN films.

  • 29.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Johnson, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Klenov, Dmitri
    FEI Company, Eindhoven, The Netherlands.
    Demeulemeester, Jelly
    École Polytechnique de Montréal, Canada.
    Desjardins, Patrick
    École Polytechnique de Montréal, Canada.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan. University of Illinois, Urbana, USA.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Nanolabyrinthine ZrAlN thin films by self-organization of interwoven single-crystal cubic and hexagonal phases2013Ingår i: APL Materials, ISSN 2166-532X, Vol. 1, nr 2, s. 022105-1-022105-6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Self-organization on the nanometer scale is a trend in materials research. Thermodynamic driving forces may, for example, yield chessboard patterns in metal alloys[Y. Ni and A. G. Khachaturyan, Nature Mater. 8, 410–414 (2009)] or nitrides [P. H.Mayrhofer, A. Horling, L. Karlsson, J. Sj ¨ ol¨ en, T. Larsson, and C. Mitterer, Appl. ´Phys. Lett. 83, 2049 (2003)] during spinodal decomposition. Here, we explore theZrN-AlN system, which has one of the largest positive enthalpies of mixing amongthe transition metal aluminum nitrides [D. Holec, R. Rachbauer, L. Chen, L. Wang,D. Luefa, and P. H. Mayrhofer, Surf. Coat. Technol. 206, 1698–1704 (2011); B.Alling, A. Karimi, and I. Abrikosov, Surf. Coat. Technol. 203, 883–886 (2008)].Surprisingly, a highly regular superhard (36 GPa) two-dimensional nanolabyrinthinestructure of two intergrown single crystal phases evolves during magnetron sputter thin film synthesis of Zr0.64Al0.36N/MgO(001). The self-organization is surfacedriven and the synergistic result of kinetic limitations, where the enthalpy reductionbalances both investments in interfacial and elastic energies.

  • 30.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Lind, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Anomalous epitaxial stability of (001) interfaces in ZrN/SiNx multilayers2014Ingår i: APL Materials, ISSN 2166-532X, Vol. 2, nr 4, s. 046106-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Isostructural stability of B1-NaCl type SiN on (001) and (111) oriented ZrN surfaces is studied theoretically and experimentally. The ZrN/SiNx/ZrN superlattices with modulation wavelength of 3.76 nm (dSiNx similar to 0.4 nm) were grown by dc-magnetron sputtering on MgO(001) and MgO(111). The results indicate that 0.4 nm thin SiNx layers utterly influence the preferred orientation of epitaxial growth: on MgO(001) cube-on-cube epitaxy of ZrN/SiNx superlattices were realized whereas multilayers on MgO(111) surface exhibited an unexpected 002 texture with a complex fourfold 90 degrees-rotated in-plane preferred orientation. Density functional theory calculations confirm stability of a (001) interface with respect to a (111) which explains the anomaly.

  • 31.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per O. Å.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Eriksson, Fredrik
    Department of Astrophysics, Columbia University, New York, New York.
    Schäfers, Franz
    BESSY GmbH, Berlin, Germany.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Interface engineered ultra-short period Cr/Ti multilayers as high reflectance mirrors and polarizers for soft X-rays of lambda=2.74 nm wavelength2006Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 45, nr 1, s. 137-143Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cr-Ti multilayers with ultrashort periods of 1.39-2.04 nm have been grown for the first time as highly reflective, soft-x-ray multilayer, near-normal incidence mirrors for transition radiation and Cherenkov radiation x-ray sources based on the Ti-2p absorption edge at E = 452eV (lambda = 2.74 nm). Hard, as well as soft, x-ay reflectivity and transmission electron microscopy were used to characterize the nanostructure of the mirrors. To achieve minimal accumulated roughness, improved interface flatness, and to avoid intermixing at the interfaces, each individual layer was engineered by use of a two-stage ion assistance process during magnetron sputter deposition: The first 0.3 nm of each Ti and Cr layer was grown without ion assistance, and the remaining 0.39-0.72 nm of the layers were grown with high ion-neutral flux ratios Phi˙(PhiTi = 3.3, PhiCr = 2.2) and a low energy Eion (ETi = 23.7 and ECr = 21.2), ion assistance. A maximum soft-x-ray reflectivity of R = 2.1% at near-normal incidence (~78.8°) was achieved for a multilayer mirror containing 100 bilayers with a modulation period of 1.379 nm and a layer thickness ratio of Gamma = 0.5. For a polarizing multilayer mirror with 150 bilayers designed for operation at the Brewster angle, 45°, an extinction ratio, Rs/Rp, of 266 was achieved with an absolute reflectivity of R = 4.3%.

  • 32.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Univ Illinois, IL 61801 USA.
    Holec, D.
    Univ Leoben, Austria.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Self-structuring in Zr1-xAlxN films as a function of composition and growth temperature2018Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, artikel-id 16327Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanostructure formation via surface-diffusion-mediated segregation of ZrN and AIN in Zr1-xAlxN films during high mobility growth conditions is investigated for 0 amp;lt;= x amp;lt;= 1. The large immiscibility combined with interfacial surface and strain energy balance resulted in a hard nanolabyrinthine lamellar structure with well-defined (semi) coherent c-ZrN and w-AlN domains of sub-nm to similar to 4 nm in 0.2 amp;lt;= x amp;lt;= 0.4 films, as controlled by atom mobility. For high AlN contents (x amp;gt; 0.49) Al-rich ZrN domains attain wurtzite structure within fine equiaxed nanocomposite wurtzite lattice. Slow diffusion in wurtzite films points towards crystal structure dependent driving force for decomposition. The findings of unlikelihood of isostructural decomposition in c-Zr1-xAlxN, and stability of w-Zr1-xAlxN (in large x films) is complemented with first principles calculations.

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  • 33.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan. University of Illinois, IL 61801 USA; University of Illinois, IL 61801 USA.
    Klenov, Dmitri O.
    FEI Co, Netherlands.
    Freitag, Bert
    FEI Co, Netherlands.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Greene, Joseph E
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan. University of Illinois, IL 61801 USA; University of Illinois, IL 61801 USA.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Self-organized anisotropic (Zr1-xSix)N-y nanocomposites grown by reactive sputter deposition2015Ingår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 82, s. 179-189Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The physical properties of hard and superhard nanocomposite thin films are strongly dependent on their nanostructure. Here, we present the results of an investigation of nanostructural evolution and the resulting mechanical properties of (Zr1-xSix)N-y films, with 0 less than= x less than= 1 and 1 less than= y less than= 1.27, grown on MgO(0 0 1) and Al2O3(0 0 0 1) substrates at temperatures T-s = 500-900 degrees C by reactive magnetron sputter deposition from Zr and Si targets. X-ray diffraction and transmission electron microscopy (TEM) results show that there is a T-s/composition window in which stoichiometric Zr-Si-N and amorphous a-Si3N4 phases mutually segregate and self-organize into encapsulated 3-5 um wide ZrN-rich (Zr1-xSix)N columns which extend along the growth direction with a strong (002) texture. Lattice-resolved scanning TEM and energy-dispersive X-ray spectroscopy reveal that the (Zr1-xSix)N-y nanocolumns are separated by a bilayer tissue phase consisting of a thin crystalline SiNy-rich (Zr1-xSix)N-y layer with an a-Si3N4 overlayer. Incorporation of metastable SiN into NaCl-structure ZrN leads to an enhanced nanoindentation hardness H which is a function of T-s and film composition. For nanocomposites with composition (Zr(0.8)Sio(0.2))N-1.14 (10 at.% Si) H, increases from 26 GPa at 500 degrees C to 37 GPa at 900 degrees C. For comparison, the hardness of epitaxial ZrN/MgO(0 0 1) layers grown at T-s = 800 degrees C is 24 GPa. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  • 34.
    Harsani, M.
    et al.
    Slovak Univ Technol Bratislava, Slovakia.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Calamba, Katherine
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Zackova, P.
    Slovak Univ Technol Bratislava, Slovakia.
    Sahul, M.
    Slovak Univ Technol Bratislava, Slovakia.
    Vopat, T.
    Slovak Univ Technol Bratislava, Slovakia.
    Satrapinskyy, L.
    Comenius Univ, Slovakia.
    Caplovicova, M.
    Slovak Univ Technol Bratislava, Slovakia.
    Caplovic, L.
    Slovak Univ Technol Bratislava, Slovakia.
    Adhesive-deformation relationships and mechanical properties of nc-AlCrN/a-SiNx hard coatings deposited at different bias voltages2018Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 650, s. 11-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of Al-Cr-Si-N hard coatings were deposited on WC-Co substrates with a negative substrate bias voltage ranging from -50 to -200 V using cathodic arc evaporation system. A Rockwell-C adhesion test demonstrated that excellent adhesion was observed at lower bias voltages of -50 V and -80 V, while further increases in bias voltage up to -200 V led to severe delamination and worsening of the overall adhesion strength. X-ray diffraction and transmission electron microscopy analysis revealed a single phase cubic B1-structure identified as an AlCrN solid solution with a nanocomposite microstructure where cubic AlCrN nanocrystals were embedded in a thin continuous amorphous SiNx matrix. Coatings exhibited a 002-texture evolution that was more pronounced at higher bias voltages (amp;gt;=-120 V). Stress-induced cracks were observed inside the coatings at high bias voltages (amp;gt;=-150 V), which resulted in stress relaxation and a decline in the overall residual stresses.

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  • 35.
    Johnson, Lars
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Engberg, David
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Thuvander, Mattias
    Dept. of Applied Physics, Chalmers University of Technology, Göteborg, Sweden.
    Stiller, Krystyna
    Chalmers University of Technology, Microscopy and Microanalysis, Department of Applied Physics, Göteborg, Sweden.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Self-organized Nanostructuring in Zr0.64Al0.36N Thin Films Studied by Atom Probe Tomography2016Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, s. 233-238Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have applied atom probe tomography (apt) to analyze the selforganized structure of wear-resistant Zr0.64Al0.36N thin films grown by magnetron sputtering. Transmission electron microscopy shows that these films grow as a two-dimensional nanocomposite, consisting of interleaved lamellae in a labyrinthine structure, with a size scale of ∼ 5 nm. The structure was recovered in the Al apt signal, while the Zr and N data lacked structural information due to severe local magnification effects. The onset of the self-organized growth was observed to occur locally by nucleation, at 5-8 nm from the MgO substrate, after increasing Zr-Al compositional fluctuations. Finally, it was observed that the self-organized growth mode could be perturbed by renucleation of ZrN.

  • 36.
    Kumar Yalamanchili, Phani
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Schramm, Isabella C.
    University of Saarland, Germany.
    Jimenez-Pique, E.
    University of Politecn Cataluna, Spain; CRnE UPC, Spain.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Muecklich, F.
    University of Saarland, Germany.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Tuning hardness and fracture resistance of ZrN/Zr0.63Al0.37N nanoscale multilayers by stress-induced transformation toughening2015Ingår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 89, s. 22-31Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Structure and mechanical properties of nanoscale multilayers of ZrN/Zr0.63Al0.37N grown by reactive magnetron sputtering on MgO (0 0 1) substrates at a temperature of 700 degrees C are investigated as a function of the Zr0.63Al0.37N layer thickness. The Zr0.63Al0.37N undergoes in situ chemical segregation into ZrN-rich and AlN-rich domains. The AlN-rich domains undergo transition from cubic to wurtzite crystal structure as a function of Zr0.63Al0.37N layer thickness. Such structural transformation allows systematic variation of hardness as well as fracture resistance of the films. A maximum fracture resistance is achieved for 2 nm thick Zr0.63Al0.37N layers where the AlN-rich domains are epitaxially stabilized in the metastable cubic phase. The metastable cubic-AlN phase undergoes stress-induced transformation to wurtzite-AlN when subjected to indentation, which results in the enhanced fracture resistance. A maximum hardness of 34 GPa is obtained for 10 nm thick Zr0.63Al0.37N layers where the wurtzite-AlN and cubic-ZrN rich domains form semi-coherent interfaces.

  • 37.
    Landälv, Ludvig
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Sandvik Coromant AB, Sweden.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ostach, Daniel
    Helmholtz Zentrum Geesthacht, Germany.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Junaid, Muhammad
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ekström, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hsiao, Ching-Lien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Leiste, Harald
    Karlsruhe Inst Technol, Germany.
    Ahlgren, Mats
    Sandvik Coromant AB, Sweden.
    Gothelid, Emmanuelle
    Sandvik Coromant AB, Sweden.
    Ailing, Bjorn
    Not Found:Linkoping Univ, Theoret Phys, Dept Phys Chem and Biol IFM, SE-58183 Linkoping, Sweden.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Stuber, Michael
    Karlsruhe Inst Technol, Germany.
    Schell, Norbert
    Helmholtz Zentrum Geesthacht, Germany.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Phase evolution of radio frequency magnetron sputtered Cr-rich (Cr,Zr)(2)O-3 coatings studied by in situ synchrotron X-ray diffraction during annealing in air or vacuum2019Ingår i: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 34, nr 22, s. 3735-3746Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The phase evolution of reactive radio frequency (RF) magnetron sputtered Cr0.28Zr0.10O0.61 coatings has been studied by in situ synchrotron X-ray diffraction during annealing under air atmosphere and vacuum. The annealing in vacuum shows t-ZrO2 formation starting at similar to 750-800 degrees C, followed by decomposition of the alpha-Cr2O3 structure in conjunction with bcc-Cr formation, starting at similar to 950 degrees C. The resulting coating after annealing to 1140 degrees C is a mixture of t-ZrO2, m-ZrO2, and bcc-Cr. The air-annealed sample shows t-ZrO2 formation starting at similar to 750 degrees C. The resulting coating after annealing to 975 degrees C is a mixture of t-ZrO2 and alpha-Cr2O3 (with dissolved Zr). The microstructure coarsened slightly during annealing, but the mechanical properties are maintained, with no detectable bcc-Cr formation. A larger t-ZrO2 fraction compared with alpha-Cr2O3 is observed in the vacuum-annealed coating compared with the air-annealed coating at 975 degrees C. The results indicate that the studied pseudo-binary oxide is more stable in air atmosphere than in vacuum.

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  • 38.
    Lind, Hans
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Forsén, Rikard
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Johansson, M P
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Improving thermal stability of hard coating films via a concept of multicomponent alloying2011Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 99, nr 9, s. 091903-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a design route for the next generation of nitride alloys via a concept of multicomponent alloying based on self-organization on the nanoscale via a formation of metastable intermediate products during the spinodal decomposition. We predict theoretically and demonstrate experimentally that quasi-ternary (TiCrAl)N alloys decompose spinodally into (TiCr)N and (CrAl)N-rich nanometer sized regions. The spinodal decomposition results in age hardening, while the presence of Cr within the AlN phase delays the formation of a detrimental wurtzite phase leading to a substantial improvement of thermal stability compared to the quasi-binary (TiAl)N or (CrAl)N alloys.

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  • 39.
    Lind, Hans
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Pilemalm, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Forsén, Rikard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Johnson, Lars
    Sandvik Coromant, Stockholm, Sweden.
    Jöesaar, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan. SECO Tools AB, Fagersta, Sweden.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    High temperature phase decomposition in TixZryAlzN2014Ingår i: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 4, nr 12, s. 127147-1-127147-9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Through a combination of theoretical and experimental observations we study the high temperature decomposition behavior of c-(TixZryAlzN) alloys. We show that for most concentrations the high formation energy of (ZrAl)N causes a strong tendency for spinodal decomposition between ZrN and AlN while other decompositions tendencies are suppressed. In addition we observe that entropic  effects due to configurational disorder favor a formation of a stable Zr-rich (TiZr)N phase with increasing temperature. Our calculations also predict that at high temperatures a Zr rich (TiZrAl)N disordered phase should become more resistant against the spinodal decomposition despite its high and positive formation energy due to the specific topology of the free energy surface at the relevant concentrations. Our experimental observations confirm this prediction by showing strong tendency towards decomposition in a Zr-poor sample while a Zr-rich alloy shows a greatly reduced decomposition rate, which is mostly attributable to binodal decomposition processes. This result highlights the importance of considering the second derivative of the free energy, in addition to its absolute value in predicting decomposition trends of thermodynamically unstable alloys.

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  • 40.
    Magnuson, Martin
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Olovsson, Weine
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Interface bonding of Zr1−xAlxN nanocomposites investigated by x-ray spectroscopies and first principles calculations2020Ingår i: Physical Review Research, E-ISSN 2643-1564, Vol. 2, nr 1Artikel, recension (Refereegranskat)
    Abstract [en]

    The electronic structure, chemical bonding, and interface component in ZrN-AlN nanocomposites formed byphase separation during thin film deposition of metastable Zr1−xAlxN (x = 0.0, 0.12, 0.26, 0.40) are investigatedby resonant inelastic x-ray scattering, x-ray emission, and x-ray absorption spectroscopy and compared to firstprinciples calculations including transitions between orbital angular momentum final states. The experimentalspectra are compared with different interface-slab model systems using first principles all-electron full-potentialcalculations where the core states are treated fully relativistically. As shown in this work, the bulk sensitivity andelement selectivity of x-ray spectroscopy enables one to probe the symmetry and orbital directions at interfacesbetween cubic and hexagonal crystals. We show how the electronic structure develops from local octahedralbond symmetry of cubic ZrN that distorts for increasing Al content into more complex bonding. This results inthree different kinds of bonding originating from semicoherent interfaces with segregated ZrN and lamellar AlNnanocrystalline precipitates. An increasing chemical shift and charge transfer between the elements takes placewith increasing Al content and affects the bond strength and increases resistivity.

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  • 41.
    Rogström, Lina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ahlgren, Mats
    Sandvik Tooling AB, 126 80 Stockholm, Sweden.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Auto-organizing ZrAlN/ZrAlTiN/TiN multilayers2012Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, nr 21, s. 6451-6454Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structural evolution during annealing of arc evaporated ZrAlN/ZrN andZrAlN/TiN multilayers is studied. On annealing, ZrN- and AlN-rich domains form within the ZrAlN sublayers. In the ZrAlN/TiN film, interdiffusion at the ZrAlN/TiN interfaces cause formation of a new cubic Zr(Al,Ti)N phase when annealed at temperatures above 900 C. The formation of this metastable phase results in a substantial increase in hardness of the film, which is retained to annealing temperatures of 1100 C. In the ZrAlN/ZrN film no secondary phases are formed and for annealing at temperatures above 800 C grain growth of the ZrN grains results in decreased hardness.

  • 42.
    Rogström, Lina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Schroeder, Jeremy
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Schell, N.
    Helmholtz Zentrum Geesthacht, Germany.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ahlgren, M.
    Sandvik Coromant, Sweden.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Thermal stability of wurtzite Zr1-xAlxN coatings studied by in situ high-energy x-ray diffraction during annealing2015Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 118, nr 3, artikel-id 035309Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the thermal stability of wurtzite (w) structure ZrAlN coatings by a combination of in situ high-energy x-ray scattering techniques during annealing and electron microscopy. Wurtzite structure Zr1-xAlxN coatings with Al-contents from x = 0.46 to x = 0.71 were grown by cathodic arc evaporation. The stability of the w-ZrAlN phase depends on chemical composition where the higher Al-content coatings are more stable. The wurtzite ZrAlN phase was found to phase separate through spinodal decomposition, resulting in nanoscale compositional modulations, i.e., alternating Al-rich ZrAlN layers and Zr-rich ZrAlN layers, forming within the hexagonal lattice. The period of the compositional modulations varies between 1.7 and 2.5 nm and depends on the chemical composition of the coating where smaller periods form in the more unstable, high Zr-content coatings. In addition, Zr leaves the w-ZrAlN lattice to form cubic ZrN precipitates in the column boundaries. (C) 2015 AIP Publishing LLC.

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  • 43.
    Rogström, Lina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Johansson, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan. Seco Tools AB, 737 82 Fagersta, Sweden.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Influence of chemical composition and deposition conditions on microstructure evolution during annealing of arc evaporated ZrAlN thin films2012Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 30, nr 3, s. 031504-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of substrate bias and chemical composition on the microstructure and hardness of arc evaporated Zr1−xAlxN films with 0.12 < x < 0.74 is investigated. A cubic ZrAlN phase is formed at low aluminum contents (x < 0.38) whereas for a high Al-content, above x=0.70, a single-phase hexagonal structure is obtained. For intermediate Al-contents, a two-phase structure is formed. The cubic structured films exhibit higher hardness than the hexagonal structured ones. A low bias results in N-rich films with a partly defect-rich microstructure while a higher substrate bias decreases the grain size and increases the residual stress in the cubic ZrAlN films. Recrystallization and out-diffusion of nitrogen from the lattice in the cubic ZrAlN films takes place during annealing at 800 C, which results in an increased hardness. The cubic ZrAlN phase is stable to annealing temperatures of 1000 C while annealing at higher temperature results in nucleation and growth of hexagonal AlN. In the high Al-content ZrAlN films, formation of ZrN- and AlN-rich domains within the hexagonal lattice during annealing at 1000 C improves the mechanical properties.

  • 44.
    Rogström, Lina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Johansson, Mats P.
    Seco Tools AB, Sweden.
    Pilemalm, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Johnson, L. J. S.
    Sandvik Coromant, Sweden.
    Schell, N.
    Helmholtz Zentrum Geesthacht, Germany.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Decomposition routes and strain evolution in arc deposited TiZrAlN coatings2019Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 779, s. 261-269Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Phase, microstructure, and strain evolution during annealing of arc deposited TiZrAlN coatings are studied using in situ x-ray scattering and ex situ transmission electron microscopy. We find that the decomposition route changes from nucleation and growth of wurtzite AlN to spinodal decomposition when the Zr-content is decreased and the Al-content increases. Decomposition of Ti0.31Zr0.24Al0.45N results in homogeneously distributed wurtzite AlN grains in a cubic, dislocation-dense matrix of TiZrN consisting of domains of different chemical composition. The combination of high dislocation density, variation of chemical composition within the cubic grains, and evenly distributed wurtzite AlN grains results in high compressive strains, -1.1%, which are retained after 3 h at 1100 degrees C. In coatings with higher Zr-content, the strains relax during annealing above 900 degrees C due to grain growth and defect annihilation. (C) 2018 Elsevier B.V. All rights reserved.

    Publikationen är tillgänglig i fulltext från 2020-11-14 12:11
  • 45.
    Schroeder, Jeremy
    et al.
    Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Thomson, W.
    PVD Prod Inc, MA 01887 USA.
    Howard, B.
    PVD Prod Inc, MA 01887 USA.
    Schell, N.
    Helmholtz Zentrum Geesthacht, Germany.
    Näslund, Lars-Åke
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Johansson-Jöesaar, Mats P.
    Seco Tools AB, Sweden.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Nothnagel, E.
    PVD Prod Inc, MA 01887 USA.
    Shepard, A.
    PVD Prod Inc, MA 01887 USA.
    Greer, J.
    PVD Prod Inc, MA 01887 USA.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Industry-relevant magnetron sputtering and cathodic arc ultra-high vacuum deposition system for in situ x-ray diffraction studies of thin film growth using high energy synchrotron radiation2015Ingår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 86, nr 9, s. 095113-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present an industry-relevant, large-scale, ultra-high vacuum (UHV) magnetron sputtering and cathodic arc deposition system purposefully designed for time-resolved in situ thin film deposition/annealing studies using high-energy (greater than50 keV), high photon flux (greater than10(12) ph/s) synchrotron radiation. The high photon flux, combined with a fast-acquisition-time (less than1 s) two-dimensional (2D) detector, permits time-resolved in situ structural analysis of thin film formation processes. The high-energy synchrotron-radiation based x-rays result in small scattering angles (less than11 degrees), allowing large areas of reciprocal space to be imaged with a 2D detector. The system has been designed for use on the 1-tonne, ultra-high load, high-resolution hexapod at the P07 High Energy Materials Science beamline at PETRA III at the Deutsches Elektronen-Synchrotron in Hamburg, Germany. The deposition system includes standard features of a typical UHV deposition system plus a range of special features suited for synchrotron radiation studies and industry-relevant processes. We openly encourage the materials research community to contact us for collaborative opportunities using this unique and versatile scientific instrument. (C) 2015 AIP Publishing LLC.

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  • 46.
    Yalamanchili, K.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Wang, Fei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Saarland University, Germany.
    Schramm, Isabella
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. Saarland University, Germany.
    Andersson, J. M.
    Seco Tools AB, Sweden.
    Johansson Jöesaar, Mats P.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Seco Tools AB, Sweden.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Muecklich, F.
    Saarland University, Germany.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Exploring the high entropy alloy concept in (AlTiVNbCr)N2017Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 636, s. 346-352Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have explored the high entropy alloy (HEA) concept in the AlTiVNbCr-nitride material system. (AlTiVNbCr)N coatings synthesized by reactive cathodic arc deposition are close to an ideal cubic solid solution with a positive mean-field enthalpy of mixing of 0.06 eV/atom. First principle calculations showa higher thermodynamic stability for the solid solution relative to their binaries thereby indicating a possible entropy stabilization at a temperature above 727 degrees C. However, the elevated temperature annealing experiments show that the solid solution decomposes to w-AlN and c-(TiVNbCr)N. The limited thermal stability of the solid solution is investigated in relation to several thermodynamic parameters. We suggest that the HEA designed multiprincipal element (AlTiVNbCr) N solid solutions are in a metastable state. (C) 2017 Published by Elsevier B.V.

  • 47.
    Yalamanchili, Kumar
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Forsén, Rikard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Jiménez-Piqué, Emilio
    Departament de Ciència del Materials i Enginyeria Metal·lúrgica, Universitat Politècnica de Catalunya, Barcelona, Spain.
    Johansson Jöesaar, Mats P.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Roa, J.J.
    Department of Materials Science and Metallurgical Engineering, University of Barcelona, Barcelona, Spain.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Structure, deformation and fracture of arc evaporated Zr-Si-N ternary hard films2014Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 258, s. 1100-1107Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Zr-Si-N films with varying Si contents were grown on WC-Co substrates with an industrial scale reactive cathodic arc deposition technique. The microstructural changes correlate to variation in mechanical properties with different deformation mechanisms dominating for different structures. Si forms a substitutional solid solution in the cubic ZrN lattice up to 1.8 at. % in a fine columnar structure. Further Si additions results in precipitation of an amorphous (a)-SiNX phase and evolution of a nanocomposite structure (nc ZrN-a SiNX) which has completely suppressed the columnar structure at 6.3 at. % Si. The rotation-induced artificial layering during film growth was used as a marker to visualize the deformation of the film. A dislocation-based homogeneous plastic deformation mechanism dominates the columnar structure, while grain boundary sliding is the active mechanism mediating heterogeneous plastic deformation in the nanocomposite structure. Film hardness increases with increasing Si content in the columnar structure due to an effective solid solution strengthening. The deformation mechanism of localized grain boundary sliding in the nanocomposite structure results in lower hardness. When cracking is induced by indentation, the fine columnar structure exhibits pronounced crack deflection that results in higher fracture resistance compared to the nanocomposite films.

  • 48.
    Yalamanchili, Kumar
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Roa, J.J.
    Department of Materials Science and Metallurgical Engineering, University of Barcelona, Barcelona, Spain.
    Jiménez-Piqué, Emilio
    Departament de Ciència del Materials i Enginyeria Metal·lúrgica, Universitat Politècnica de Catalunya, Barcelona, Spain.
    Johansson Jöesaar, Matts P.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Influence of microstructure and mechanical properties on the wear behavior of reactive arc deposited Zr-Si-N coatingsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Zr-Si-N coatings were grown over WC-Co substrates by an industrial reactive arc deposition technique. Si content of the coatings was varied between 0.2 and 6.3 at. % to cause a microstructural transition from a columnar to an equiaxed nanocomposite microstructure resulting in alterations of the mechanical properties such as hardness, elastic modulus, and fracture resistance. A reciprocating sliding wear test with a counter material of WC-Co shows a systematic change in wear rate as a function of Si content of the coatings. A maximum wear rate of 1.4x10-5 mm3/Nm is seen for the coating with 1.8 at. % Si (columnar microstructure), which then gradually decreases to 0.6x10-5 mm3/Nm at 6.3 at. % Si (nanocomposite structure). Electron microscopy observations of the wear track reveal tribooxidation as the dominating wear mode. The growth rate of the tribo-oxide layer is the wear rate determining mechanism. Higher growth rate of tribo-oxide layer in the columnar structured coating leads to layer delamination and high wear rate. While the lower growth rate of tribo-oxide layer in the nanocomposite coating results in reduced wear rate of the coatings. Nanocomposite coatings show superior resistance to both static and tribo-oxidation compared to the columnar structured coatings.

  • 49.
    Yalamanchili, Kumar
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Schramm, I.C.
    Functional Materials, Materials Science and Engineering Department (MSE), Saarland University, Saarbrücken, Germany.
    Jiménez-Piqué, Emilio
    Departament de Ciència del Materials i Enginyeria Metal·lúrgica, Universitat Politècnica de Catalunya, Barcelona, Spain.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Mücklich, F.
    Functional Materials, Materials Science and Engineering Department (MSE), Saarland University, Saarbrücken, Germany.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Growth and Mechanical Behavior of Nanoscale Structures in ZrN/Zr0.63Al0.37N MultilayersManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Structure and mechanical properties of monolithic and nanoscale multilayers of ZrN/Zr0.63Al0.37N are investigated as a function of Zr0.63Al0.37N layer thickness. ZrN/Zr0.63Al0.37N multilayers were deposited by reactive magnetron sputtering on MgO (001) substrates at a temperature of 700 °C. Monolithic Zr0.63Al0.37N film shows a chemically segregated nanostructure of cubic-ZrN and wurtzite-AlN rich domains with incoherent interfaces. Three dimensional atom probe measurements reveal comparable chemical segregation between monolithic and multilayer Zr0.63Al0.37N film. The multilayers show systematic changes in nanostructure as a function of Zr0.63Al0.37N layer thickness resulting in mechanical properties such as hardness and fracture resistance being tunable. A maximum hardness of 34 GPa is achieved with 10 nm Zr0.63Al0.37N layer thickness having semi-coherent interfaces between wurtzite-AlN and cubic-ZrN rich domains. Higher fracture resistance is achieved at 2nm Zr0.63Al0.37N where AlN rich domains are epitaxially stabilized in the metastable cubic phase.

  • 50.
    Yalamanchili, Phani Kumar
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, Center for Research in Nanoengineering, CRnE-UPC Avda, Barcelona, Spain.
    Jimenez-Pique, E.
    Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, Center for Research in Nanoengineering, CRnE-UPC Avda, Barcelona, Spain.
    Pelcastre, L.
    Division of Machine Elements, Luleå University of Technology, Luleå, Sweden.
    Bakoglidis, Konstantinos
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Roa, J. J.
    Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, Center for Research in Nanoengineering, CRnE-UPC Avda, Barcelona, Spain.
    Johansson Joesaar, M. P.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. Seco Tools AB, Fagersta, Sweden.
    Prakash, B.
    Division of Machine Elements, Luleå University of Technology, Luleå, Sweden.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Influence of microstructure and mechanical properties on the tribological behavior of reactive arc deposited Zr-Si-N coatings at room and high temperature2016Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 304, s. 393-400Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Varying the Si-content in Zr-Si-N coatings from 0.2 to 6.3 at.% causes microstructural changes from columnar to nanocomposite structure and a hardness drop from 37 to 26 GPa. The softer nanocomposite also displays lower fracture resistance. The tribological response of these coatings is investigated under different contact conditions, both at room and elevated temperatures. At room temperature tribooxidation is found to be the dominant wear mechanism, where the nanocomposite coatings display the lowest wear rate of 0.64 x 10(-5) mm(3)/Nm, by forming an oxide diffusion barrier layer consisting of Zr, W, and Si. A transition in the dominant wear mechanism from tribooxidation to microploughing is observed upon increasing the test temperature and contact stress. Here, all coatings exhibit significantly higher coefficient of friction of 1.4 and the hardest coatings with columnar structure display the lowest wear rate of 10.5 x 10(-5) mm(3)/Nm. In a microscopic wear test under the influence of contact-induced dominant elastic stress field, the coatings display wedge formation and pileup due to accumulation of the dislocation-induced plastic deformation. In these tests, the nanocomposite coatings display the lowest wear rate of 0.56 x 10(-10) mm(3)/Nm, by constraining the dislocation motion. (C) 2016 Elsevier B.V. All rights reseved.

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