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  • 1.
    Abrikosov, Igor A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Steneteg, Peter
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Hultberg, Lasse
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Hellman, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Yu Mosyagin, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Department of Theoretical Physics and Quantum Technologies, National Research, Technological University MISiS, Moscow, Russia.
    Lugovskoy, Andrey V.
    Department of Theoretical Physics and Quantum Technologies, National Research, Technological University MISiS, Russia.
    Barannikova, Svetlana A.
    Institute of Strength Physics and Materials Science, Siberian Branch of Russian Academy of Science, Tomsk, Russia; Department of Physics and Engineering, Tomsk State University, Tomsk, Russia.
    Finite Temperature, Magnetic, and Many-Body Effects in Ab Initio Simulations of Alloy Thermodynamics2013In: TMS2013 Supplemental Proceedings, John Wiley & Sons, 2013, p. 617-626Chapter in book (Refereed)
    Abstract [en]

    Ab initio electronic structure theory is known as a useful tool for prediction of materials properties. However, majority of simulations still deal with calculations in the framework of density functional theory with local or semi-local functionals carried out at zero temperature. We present new methodological solution.s, which go beyond this approach and explicitly take finite temperature, magnetic, and many-body effects into account. Considering Ti-based alloys, we discuss !imitations of the quasiharmonic approximation for the treatment of lattice vibrations, and present an accurate and easily extendable method to calculate free ,energies of strongly anharmonic solids. We underline the necessity to going beyond the state-of-the-art techniques for the determination of effective cluster interactions in systems exhibiting mctal-to-insulator transition, and describe a unified cluster expansion approach developed for this class of materials. Finally, we outline a first-principles method, disordered local moments molecular dynamics, for calculations of thermodynamic properties of magnetic alloys, like Cr1-x,.AlxN, in their high-temperature paramagnetic state. Our results unambiguously demonstrate importance of finite temperature effects in theoretical calculations ofthermodynamic properties ofmaterials.

  • 2.
    Adranno, Brando
    et al.
    Stockholm Univ, Sweden.
    Renier, Olivier
    Stockholm Univ, Sweden.
    Bousrez, Guillaume
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering. Stockholm Univ, Sweden.
    Paterlini, Veronica
    Stockholm Univ, Sweden.
    Baryshnikov, Glib
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Smetana, Volodymyr
    Stockholm Univ, Sweden.
    Tang, Shi
    Umea Univ, Sweden.
    agren, Hans
    Uppsala Univ, Sweden.
    Metlen, Andreas
    Queens Univ Belfast, North Ireland.
    Edman, Ludvig
    Umea Univ, Sweden.
    Anja-Verena, Mudring
    Stockholm Univ, Sweden; Aarhus Univ, Denmark.
    Rogers, Robin D.
    Stockholm Univ, Sweden; Queens Univ Belfast, North Ireland; Univ Alabama, AL 35487 USA.
    The 8-Hydroxyquinolinium Cation as a Lead Structure for Efficient Color-Tunable Ionic Small Molecule Emitting Materials2023In: ADVANCED PHOTONICS RESEARCH, ISSN 2699-9293, Vol. 4, no 3, article id 2200279Article in journal (Refereed)
    Abstract [en]

    Albeit tris(8-hydroxyquinolinato) aluminum (Alq(3)) and its derivatives are prominent emitter materials for organic lighting devices, and the optical transitions occur among ligand-centered states, the use of metal-free 8-hydroxyquinoline is impractical as it suffers from strong nonradiative quenching, mainly through fast proton transfer. Herein, it is shown that the problem of rapid proton exchange and vibration quenching of light emission can be overcome not only by complexation, but also by organization of the 8-hydroxyquinolinium cations into a solid rigid network with appropriate counter-anions (here bis(trifluoromethanesulfonyl)imide). The resulting structure is stiffened by secondary bonding interactions such as pi-stacking and hydrogen bonds, which efficiently block rapid proton transfer quenching and reduce vibrational deactivation. Additionally, the optical properties are tuned through methyl substitution from deep blue (455 nm) to blue-green (488 nm). Time-dependent density functional theory (TDFT) calculations reveal the emission to occur from which an unexpectedly long-lived S-1 level, unusual for organic fluorophores. All compounds show comparable, even superior photoluminescence compared to Alq(3) and related materials, both as solids and thin films with quantum yields (QYs) up to 40-50%. In addition, all compounds show appreciable thermal stability with decomposition temperatures above 310 degrees C.

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  • 3.
    Ahvenniemi, Esko
    et al.
    Aalto University, Finland.
    Akbashev, Andrew R.
    Stanford University, CA 94305 USA.
    Ali, Saima
    Aalto University, Finland.
    Bechelany, Mikhael
    University of Montpellier, France.
    Berdova, Maria
    University of Twente, Netherlands.
    Boyadjiev, Stefan
    Bulgarian Academic Science, Bulgaria.
    Cameron, David C.
    Masaryk University, Czech Republic.
    Chen, Rong
    Huazhong University of Science and Technology, Peoples R China.
    Chubarov, Mikhail
    University of Grenoble Alpes, France.
    Cremers, Veronique
    University of Ghent, Belgium.
    Devi, Anjana
    Ruhr University of Bochum, Germany.
    Drozd, Viktor
    St Petersburg State University, Russia.
    Elnikova, Liliya
    Institute Theoret and Expt Phys, Russia.
    Gottardi, Gloria
    Fdn Bruno Kessler, Italy.
    Grigoras, Kestutis
    VTT Technical Research Centre Finland, Finland.
    Hausmann, Dennis M.
    Lam Research Corp, OR 97062 USA.
    Seong Hwang, Cheol
    Seoul National University, South Korea; Seoul National University, South Korea.
    Jen, Shih-Hui
    Globalfoundries, NY 12203 USA.
    Kallio, Tanja
    Aalto University, Finland.
    Kanervo, Jaana
    Aalto University, Finland; Abo Akad University, Finland.
    Khmelnitskiy, Ivan
    St Petersburg Electrotech University of LETI, Russia.
    Han Kim, Do
    MIT, MA 02139 USA.
    Klibanov, Lev
    Techinsights, Canada.
    Koshtyal, Yury
    Ioffe Institute, Russia.
    Krause, A. Outi I.
    Aalto University, Finland.
    Kuhs, Jakob
    University of Ghent, Belgium.
    Kaerkkaenen, Irina
    Sentech Instruments GmbH, Germany.
    Kaariainen, Marja-Leena
    NovaldMedical Ltd Oy, Finland.
    Kaariainen, Tommi
    NovaldMedical Ltd Oy, Finland; University of Helsinki, Finland.
    Lamagna, Luca
    STMicroelectronics, Italy.
    Lapicki, Adam A.
    Seagate Technology Ireland, North Ireland.
    Leskela, Markku
    University of Helsinki, Finland.
    Lipsanen, Harri
    Aalto University, Finland.
    Lyytinen, Jussi
    Aalto University, Finland.
    Malkov, Anatoly
    Technical University, Russia.
    Malygin, Anatoly
    Technical University, Russia.
    Mennad, Abdelkader
    CDER, Algeria.
    Militzer, Christian
    Technical University of Chemnitz, Germany.
    Molarius, Jyrki
    Summa Semicond Oy, Finland.
    Norek, Malgorzata
    Mil University of Technology, Poland.
    Ozgit-Akgun, Cagla
    ASELSAN Inc, Turkey.
    Panov, Mikhail
    St Petersburg Electrotech University of LETI, Russia.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Piallat, Fabien
    KOBUS, France.
    Popov, Georgi
    University of Helsinki, Finland.
    Puurunen, Riikka L.
    VTT Technical Research Centre Finland, Finland.
    Rampelberg, Geert
    University of Ghent, Belgium.
    Ras, Robin H. A.
    Aalto University, Espoo, Finland.
    Rauwel, Erwan
    Tallinn University of Technology, Estonia.
    Roozeboom, Fred
    Eindhoven University of Technology, Netherlands; TNO, Netherlands.
    Sajavaara, Timo
    University of Jyvaskyla, Finland.
    Salami, Hossein
    University of Maryland, MD 20742 USA.
    Savin, Hele
    Aalto University, Finland.
    Schneider, Nathanaelle
    IRDEP CNRS, France; IPVF, France.
    Seidel, Thomas E.
    Seitek50, FL 32135 USA.
    Sundqvist, Jonas
    Fraunhofer Institute Ceram Technology and Syst IKTS, Germany.
    Suyatin, Dmitry B.
    Lund University, Sweden; Lund University, Sweden.
    Torndahl, Tobias
    Uppsala University, Sweden.
    van Ommen, J. Ruud
    Delft University of Technology, Netherlands.
    Wiemer, Claudia
    CNR, Italy.
    Ylivaara, Oili M. E.
    VTT Technical Research Centre Finland, Finland.
    Yurkevich, Oksana
    Immanuel Kant Balt Federal University, Russia.
    Recommended reading list of early publications on atomic layer deposition-Outcome of the "Virtual Project on the History of ALD"2017In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 35, no 1, article id 010801Article, review/survey (Refereed)
    Abstract [en]

    Atomic layer deposition (ALD), a gas-phase thin film deposition technique based on repeated, self-terminating gas-solid reactions, has become the method of choice in semiconductor manufacturing and many other technological areas for depositing thin conformal inorganic material layers for various applications. ALD has been discovered and developed independently, at least twice, under different names: atomic layer epitaxy (ALE) and molecular layering. ALE, dating back to 1974 in Finland, has been commonly known as the origin of ALD, while work done since the 1960s in the Soviet Union under the name "molecular layering" (and sometimes other names) has remained much less known. The virtual project on the history of ALD (VPHA) is a volunteer-based effort with open participation, set up to make the early days of ALD more transparent. In VPHA, started in July 2013, the target is to list, read and comment on all early ALD academic and patent literature up to 1986. VPHA has resulted in two essays and several presentations at international conferences. This paper, based on a poster presentation at the 16th International Conference on Atomic Layer Deposition in Dublin, Ireland, 2016, presents a recommended reading list of early ALD publications, created collectively by the VPHA participants through voting. The list contains 22 publications from Finland, Japan, Soviet Union, United Kingdom, and United States. Up to now, a balanced overview regarding the early history of ALD has been missing; the current list is an attempt to remedy this deficiency. (C) 2016 Author(s).

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  • 4.
    Ail, Ujwala
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Wang, Hui
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Thermoelectric Properties of Polymeric Mixed Conductors2016In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 34, p. 6288-6296Article in journal (Refereed)
    Abstract [en]

    The thermoelectric (TE) phenomena are intensively explored by the scientific community due to the rather inefficient way energy resources are used with a large fraction of energy wasted in the form of heat. Among various materials, mixed ion-electron conductors (MIEC) are recently being explored as potential thermoelectrics, primarily due to their low thermal conductivity. The combination of electronic and ionic charge carriers in those inorganic or organic materials leads to complex evolution of the thermovoltage (Voc) with time, temperature, and/or humidity. One of the most promising organic thermoelectric materials, poly(3,4-ethyelenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS), is an MIEC. A previous study reveals that at high humidity, PEDOT-PSS undergoes an ionic Seebeck effect due to mobile protons. Yet, this phenomenon is not well understood. In this work, the time dependence of the Voc is studied and its behavior from the contribution of both charge carriers (holes and protons) is explained. The presence of a complex reorganization of the charge carriers promoting an internal electrochemical reaction within the polymer film is identified. Interestingly, it is demonstrated that the time dependence behavior of Voc is a way to distinguish between three classes of polymeric materials: electronic conductor, ionic conductor, and mixed ionic–electronic conductor

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  • 5.
    Akbar, Fariia Iasmin
    et al.
    Univ Bayreuth, Germany; Univ Bayreuth, Germany.
    Aslandukova, Alena
    Univ Bayreuth, Germany.
    Aslandukov, Andrey
    Univ Bayreuth, Germany; Univ Bayreuth, Germany.
    Yin, Yuqing
    Univ Bayreuth, Germany; Shandong Univ, Peoples R China.
    Trybel, Florian
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Khandarkhaeva, Saiana
    Univ Bayreuth, Germany.
    Fedotenko, Timofey
    Deutsch Elektronen Synchrotron DESY, Germany.
    Laniel, Dominique
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    Bykov, Maxim
    Univ Cologne, Germany.
    Bykova, Elena
    Univ Bayreuth, Germany.
    Doubrovinckaia, Natalia
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Univ Bayreuth, Germany.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    High-pressure synthesis of dysprosium carbides2023In: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 11, article id 1210081Article in journal (Refereed)
    Abstract [en]

    Chemical reactions between dysprosium and carbon were studied in laser-heated diamond anvil cells at pressures of 19, 55, and 58 GPa and temperatures of similar to 2500 K. In situ single-crystal synchrotron X-ray diffraction analysis of the reaction products revealed the formation of novel dysprosium carbides, Dy4C3 and Dy3C2, and dysprosium sesquicarbide Dy2C3 previously known only at ambient conditions. The structure of Dy4C3 was found to be closely related to that of dysprosium sesquicarbide Dy2C3 with the Pu2C3-type structure. Ab initio calculations reproduce well crystal structures of all synthesized phases and predict their compressional behavior in agreement with our experimental data. Our work gives evidence that high-pressure synthesis conditions enrich the chemistry of rare earth metal carbides.

  • 6. Alfredsson, Maria
    et al.
    Ojamae, Lars
    Hermansson, Kersti
    Uppsala universitet, Strukturkemi.
    A comparison of Hartree-Fock, MP2, and DFT results for the HCN dimer and crystal1996In: INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Vol. 60, no 3, p. 767-777Article in journal (Refereed)
    Abstract [en]

    A number of hydrogen-bond related quantities-geometries, interaction energies, dipole moments, dipole moment derivatives, and harmonic vibrational frequencies-were calculated at the Hartree-Fock, MP2, and different DFT levels for the HCN dimer and the pe

  • 7.
    Ali, Amjad
    et al.
    COMSATS Univ Islamabad, Pakistan; Univ Okara, Pakistan.
    Munir, Sajid
    Univ Okara, Pakistan.
    Majeed, Mubushar
    Univ Okara, Pakistan.
    Khalil, Arif
    Bahauddin Zakariya Univ, Pakistan.
    Hussain, Muhammad Iqbal
    Univ Education, Pakistan.
    Raza, Rizwan
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. COMSATS Univ Islamabad, Pakistan.
    Effect of Manganese Catalysts on the Performance of Anodes in Direct Carbon Fuel Cells2022In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 5, no 6, p. 6878-6885Article in journal (Refereed)
    Abstract [en]

    The efficiency of direct carbon fuel cells is higher than that of solid oxide fuel cells. The direct carbon fuel cell transforms chemical energy into electrical energy. In this work, the La0.4Sr0.6MnxTi1-xO3-delta (x = 0.02, 0.04, 0.06, 0.08) anode material has been synthesized by the combustion method to examine the device performance. X-ray analysis confirmed the single-perovskite cubic structure with an average crystalline size of 80 nm. An electrical conductivity of 2.1 S cm-1 and fuel cell performance of 100 mW cm-2 at 600 degrees C are measured with sub-bituminous fuel. Theoretical results describe the minor contribution of manganese (Mn) in the valence band and the major one in the conduction band, and with minimum energy, the Mn electrons may jump in the conduction band. Moreover, density functional theory confirmed that with an increase in the Mn concentration, Mn and Ti energy states appear at the Fermi level, which reveals that the conductivity of the compound has improved, agreeing with the experimental results that the Mn concentration led to the enhancement of the conductivity.

  • 8.
    Ali Kamyabi, Mohammad
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Zanjan University, Iran.
    Hajari, Nasim
    Zanjan University, Iran.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Tiwari, Ashutosh
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Correction: A high-performance glucose biosensor using covalently immobilised glucose oxidase on a poly(2,6-diaminopyridine)/carbon nanotube electrode (vol 116, pg 801, 2013)2016In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 153, p. 414-415Article in journal (Refereed)
    Abstract [en]

    A highly-sensitive glucose biosensor amenable to ultraminiaturisation was fabricated by immobilization of glucose oxidase (wGOX), onto a poly(2,6-diaminopyridine)/multi-walled carbon nanotube/glassy carbon electrode (poly(2,6-DP)/MWCNT/GCE). Cyclic voltammetry was used for both the electrochemical synthesis of poly-(2,6-DP) on the surface of a MWCNT-modified GC electrode, and characterization of the polymers deposited on the GC electrode. The synergistic effect of the high active surface area of both the conducting-polymer, i.e., poly-(2,6-DP) and MWCNT gave rise to a remarkable improvement in the electrocatalytic properties of the biosensor. The transfer coefficient (alpha), heterogeneous electron transfer rate constant and Michaelis-Menten constant were calculated to be 0.6, 4 s-1 and 0.22 mM at pH 7.4, respectively. The GOx/poly(2,6-DP)/MWCNT/GC bioelectrode exhibited two linear responses to glucose in the concentration ranging from 0.42 mu M to 8.0 mM with a correlation coefficient of 0.95, sensitivity of 52.0 mu AmM-1 cm-2, repeatability of 1.6% and long-term stability, which could make it a promising bioelectrode for precise detection of glucose in the biological samples. (C) 2016 Elsevier B.V. All rights reserved.

  • 9.
    Ali, Sharafat
    et al.
    Linnaeus Univ, Sweden.
    Paul, Biplab
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ekström, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Pallier, Camille
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. RISE IVF, S-58188 Linkoping, Sweden.
    Jonson, Bo
    Linnaeus Univ, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Optical and mechanical properties of amorphous Mg-Si-O-N thin films deposited by reactive magnetron sputtering2019In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 372, p. 9-15Article in journal (Refereed)
    Abstract [en]

    In this work, amorphous thin films in Mg-Si-O-N system typically containing amp;gt; 15 at.% Mg and 35 at.% N were prepared in order to investigate especially the dependence of optical and mechanical properties on Mg composition. Reactive RF magnetron co-sputtering from magnesium and silicon targets were used for the deposition of Mg-Si-O-N thin films. Films were deposited on float glass, silica wafers and sapphire substrates in an Ar, N-2 and O-2 gas mixture. X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, spectroscopic ellipsometry, and nanoindentation were employed to characterize the composition, surface morphology, and properties of the films. The films consist of N and Mg contents up to 40 at.% and 28 at.%, respectively and have good adhesion to substrates and are chemically inert. The thickness and roughness of the films increased with increasing content of Mg. Both hardness (16-21 GPa) and reduced elastic modulus (120-176 GPa) are strongly correlated with the amount of Mg content. The refractive index up to 2.01 and extinction coefficient up to 0.18 were found to increase with Mg content. The optical band gap (3.1-4.3) decreases with increasing the Mg content. Thin film deposited at substrate temperature of 100 degrees C shows a lower value of hardness (10 GPa), refractive index (1.75), and higher values of reduced elastic modulus (124 GPa) as compared to the thin film deposited at 310 degrees C and 510 degrees C respectively, under identical synthesis parameters.

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  • 10.
    Ali, Sharafat
    et al.
    Linnaeus University, Sweden.
    Paul, Biplab
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Broitman, Esteban
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Jonson, Bo
    Linnaeus University, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Novel transparent Mg-Si-O-N thin films with high hardness and refractive index2016In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 131Article in journal (Refereed)
    Abstract [en]

    There is an increasing demand for glass materials with better mechanical and optical properties for display and electronic applications. This paper describes the deposition of novel thin films of Mg-circle divide-Si-O-N onto float glass substrates. Amorphous thin films in the Mg-Si-O-N system with high nitrogen and magnesium contents were deposited by reactive RF magnetron co-sputtering from Mg and Si targets in Ar/N-2/O-2 gas mixtures. The thin films studied span an unprecedented range of compositions up to 45 at% Mg and 80 at% N out of cations and anions respectively. Thin films in the Mg-Si-O-N system were found to be homogeneous and transparent in the visible region. Mechanical properties like hardness (H) and reduced elastic modulus (Er) show high values, up to 21 GPa and 166 GPa respectively. The refractive index (1.87-2.00) increases with increasing magnesium and nitrogen contents. (C) 2016 Elsevier Ltd. All rights reserved.

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  • 11.
    Alijan Farzad Lahiji, Faezeh
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Bairagi, Samiran
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sortica, Mauricio A.
    Uppsala Univ, Sweden.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden.
    Ekström, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Paul, Biplab
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Growth and optical properties of NiO thin films deposited by pulsed dc reactive magnetron sputtering2023In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 41, no 6, article id 063402Article in journal (Refereed)
    Abstract [en]

    NiO thin films with varied oxygen contents are grown on Si(100) and c-Al2O3 at a substrate temperature of 300 degrees C using pulsed dc reactive magnetron sputtering. We characterize the structure and optical properties of NiO changes as functions of the oxygen content. NiO with the cubic structure, single phase, and predominant orientation along (111) is found on both substrates. X-ray diffraction and pole figure analysis further show that NiO on the Si(100) substrate exhibits fiber-textured growth, while twin domain epitaxy was achieved on c-Al2O3, with NiO(111) k Al2O3(0001) and NiO[1 (1) over bar0]k Al2O3[10 (1) over bar0] or NiO[(1) over bar 10]k Al2O3[2 (1) over bar(1) over bar0] epitaxial relationship. The oxygen content in NiO films did not have a significant effect on the refractive index, extinction coefficient, and absorption coefficient. This suggests that the optical properties of NiO films remained unaffected by changes in the oxygen content.

  • 12.
    Anasori, Babak
    et al.
    Drexel Univ, PA 19104 USA; Drexel Univ, PA 19104 USA.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rivin, Oleg
    Nucl Res Ctr Negev, Israel.
    Dahlqvist, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Voigt, Cooper
    Drexel Univ, PA 19104 USA.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barsoum, Michel W.
    Drexel Univ, PA 19104 USA.
    Caspi, Elad N.
    Drexel Univ, PA 19104 USA; Nucl Res Ctr Negev, Israel.
    A Tungsten-Based Nanolaminated Ternary Carbide: (W,Ti)(4)C4-x2019In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, no 2, p. 1100-1106Article in journal (Refereed)
    Abstract [en]

    Nanolamellar transition metal carbides are gaining increasing interests because of the recent developments of their twodimensional (2D) derivatives and promising performance for a variety of applications from energy storage, catalysis to transparent conductive coatings, and medicine. To develop more novel 2D materials, new nanolaminated structures are needed. Here we report on a tungsten based nanolaminated ternary phase, (W,Ti)(4)C4-x, synthesized by an Al catalyzed reaction of W, Ti, and C powders at 1600 degrees C for 4 h, under flowing argon. X-ray and neutron diffraction, along with Z-contrast scanning transmission electron microscopy, were used to determine the atomic structure, ordering, and occupancies. This phase has a layered hexagonal structure (P6(3)/mmc) with lattice parameters, a = 3.00880(7) angstrom, and c = 19.5633(6) angstrom and a nominal chemistry of (W,Ti)(4)C4-x (actual chemistry, W2.1(1)Ti1.6(1)C2.6(1)). The structure is comprised of layers of pure W that are also twin planes with two adjacent atomic layers of mixed W and Ti, on either side. The use of Al as a catalyst for synthesizing otherwise difficult to make phases, could in turn lead to the discovery of a large family of nonstoichiometric ternary transition metal carbides, synthesized at relatively low temperatures and shorter times.

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  • 13.
    Andersson, Olof
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Ulrich, Christian
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Björefors, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Imaging SPR for detection of local electrochemical processes on patterned surfaces2008In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 134, no 2, p. 545-550Article in journal (Refereed)
    Abstract [en]

    Imaging surface plasmon resonance (iSPR) was used in conjunction with voltammetry to investigate the possibility of detecting local electrochemical processes in situ on chemically modified electrodes. More specifically, a pattern of self-assembled monolayers (SAMs) of thiocholesterol and 1-hexadecanethiol was microcontact printed on gold substrates, and the blocking characteristics on different parts of the pattern were investigated. The SPR images reflected the changes in the refractive index over the working electrode due to electrochemical processes, which in the present case showed the ability of the SAMs to impede faradaic reactions. The results show that differences in packing densities or porosity of SAMs in different regions of a patterned surface can be visualized as electrochemical images using iSPR. The strength of utilizing an optical detection method for electrochemical characterization lies in the ability to achieve lateral resolution in real-time. Electrochemical reactions can also be used to enhance the contrast in SPR images of thin layers of components with similar thicknesses and refractive indices.

  • 14.
    Ask, Per
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Edwall, G
    Johansson, K E
    Accuracy and choice of procedures in 24-hour oesophageal pH monitoring with monocrystalline antimony electrodes.1986In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 24, no 6, p. 602-608Article in journal (Refereed)
    Abstract [en]

    In 24 h pH monitoring, the evaluation is dependent on the absolute accuracy of the pH measurements. Several sources of error exist, such as the chemical composition of calibration buffers and reference electrode gel and the effect of temperature on both the pH and the reference electrodes. We investigated the magnitude of these errors for the monocrystalline antimony electrode. Similar analysis applies to other types of pH electrodes. The errors we found are important when choosing a calibration procedure. We recommend a calibration procedure in which the pH and reference electrodes are both put in a beaker with the calibration buffers prior to and after the 24 h measurements. The calibration buffers and the electrode gel should have a specially selected ion composition where, for example, the Cl-ion concentration is critical. Corrections for differences in temperature between the calibration and the in situ measurements must be added. The pH measurements can be checked by performing in situ calibration.

  • 15.
    Aslandukov, Andrey
    et al.
    Univ Bayreuth, Germany.
    Aslandukova, Alena
    Univ Bayreuth, Germany.
    Laniel, Dominique
    Univ Bayreuth, Germany.
    Koemets, Iuliia
    Univ Bayreuth, Germany.
    Fedotenko, Timofey
    Univ Bayreuth, Germany.
    Yuan, Liang
    Univ Bayreuth, Germany.
    Steinle-Neumann, Gerd
    Univ Bayreuth, Germany.
    Glazyrin, Konstantin
    Deutsch Elekt Synchrotron, Germany.
    Hanfland, Michael
    European Synchrotron Radiat Facil, France.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    Doubrovinckaia, Natalia
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Univ Bayreuth, Germany.
    High-Pressure Yttrium Nitride, Y5N14, Featuring Three Distinct Types of Nitrogen Dimers2021In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 125, no 32, p. 18077-18084Article in journal (Refereed)
    Abstract [en]

    Yttrium nitride, Y5N14, was synthesized by direct reaction between yttrium and nitrogen at similar to 50 GPa and similar to 2000 K in a laser-heated diamond anvil cell. High-pressure single-crystal X-ray diffraction revealed that the crystal structure of Y5N14 (space group P4/mbm) contains three distinct types of nitrogen dimers. Crystal chemical analysis and ab initio calculations demonstrated that the dimers [N-2](x-) are crystallographically and chemically nonequivalent and possess distinct noninteger formal charges (x) that make Y5N14 unique among known compounds. Theoretical computations showed that Y5N14 has an anion-driven metallicity, with the filled part of its conduction band formed by nitrogen p-states. The compressibility of Y5N14, determined on decompression down to similar to 10 GPa, was found to be uncommonly high for dinitrides containing +3 cations (the bulk modulus K-0 = 137(6) GPa).

  • 16.
    Aslandukov, Andrey
    et al.
    Univ Bayreuth, Germany.
    Jurzick, Pascal L.
    Univ Cologne, Germany.
    Bykov, Maxim
    Univ Cologne, Germany.
    Aslandukova, Alena
    Univ Bayreuth, Germany.
    Chanyshev, Artem
    Univ Bayreuth, Germany.
    Laniel, Dominique
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    Yin, Yuqing
    Univ Bayreuth, Germany.
    Akbar, Fariia I.
    Univ Bayreuth, Germany.
    Khandarkhaeva, Saiana
    Univ Bayreuth, Germany.
    Fedotenko, Timofey
    Deutsch Elektronen Synchrotron DESY, Germany.
    Glazyrin, Konstantin
    Deutsch Elektronen Synchrotron DESY, Germany.
    Chariton, Stella
    Univ Chicago, IL 60637 USA.
    Prakapenka, Vitali
    Univ Chicago, IL 60637 USA.
    Wilhelm, Fabrice
    European Synchrotron Radiat Facil, France.
    Rogalev, Andrei
    European Synchrotron Radiat Facil, France.
    Comboni, Davide
    European Synchrotron Radiat Facil, France.
    Hanfland, Michael
    European Synchrotron Radiat Facil, France.
    Doubrovinckaia, Natalia
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Univ Bayreuth, Germany.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    Stabilization Of The CN35− Anion In Recoverable High-pressure Ln3O2(CN3) (Ln=La, Eu, Gd, Tb, Ho, Yb) Oxoguanidinates2023In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773Article in journal (Refereed)
    Abstract [en]

    A series of isostructural Ln(3)O(2)(CN3) (Ln=La, Eu, Gd, Tb, Ho, Yb) oxoguanidinates was synthesized under high-pressure (25-54 GPa) high-temperature (2000-3000 K) conditions in laser-heated diamond anvil cells. The crystal structure of this novel class of compounds was determined via synchrotron single-crystal X-ray diffraction (SCXRD) as well as corroborated by X-ray absorption near edge structure (XANES) measurements and density functional theory (DFT) calculations. The Ln(3)O(2)(CN3) solids are composed of the hitherto unknown CN35- guanidinate anion-deprotonated guanidine. Changes in unit cell volumes and compressibility of Ln(3)O(2)(CN3) (Ln=La, Eu, Gd, Tb, Ho, Yb) compounds are found to be dictated by the lanthanide contraction phenomenon. Decompression experiments show that Ln(3)O(2)(CN3) compounds are recoverable to ambient conditions. The stabilization of the CN35- guanidinate anion at ambient conditions provides new opportunities in inorganic and organic synthetic chemistry.

  • 17.
    Aslandukova, Alena
    et al.
    Univ Bayreuth, Germany.
    Aslandukov, Andrey
    Univ Bayreuth, Germany.
    Yuan, Liang
    Univ Bayreuth, Germany.
    Laniel, Dominique
    Univ Bayreuth, Germany.
    Khandarkhaeva, Saiana
    Univ Bayreuth, Germany.
    Fedotenko, Timofey
    Univ Bayreuth, Germany.
    Steinle-Neumann, Gerd
    Univ Bayreuth, Germany.
    Glazyrin, Konstantin
    DESY, Germany.
    Doubrovinckaia, Natalia
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Univ Bayreuth, Germany.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    Novel High-Pressure Yttrium Carbide gamma-Y4C5 Containing [C-2] and Nonlinear [C-3] Units with Unusually Large Formal Charges2021In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 127, no 13, article id 135501Article in journal (Refereed)
    Abstract [en]

    Changes in the bonding of carbon under high pressure leads to unusual crystal chemistry and can dramatically alter the properties of transition metal carbides. In this work, the new orthorhombic polymorph of yttrium carbide, gamma-Y4C5, was synthesized from yttrium and paraffin oil in a laser-heated diamond anvil cell at similar to 50 GPa. The structure of gamma-Y4C5 was solved and refined using in situ synchrotron single-crystal x-ray diffraction. It includes two carbon groups: [C-2] dimers and nonlinear [C-3] trimers. Crystal chemical analysis and density functional theory calculations revealed unusually high noninteger charges ([C-2](5.2-) and [C-3](6.8-)) and unique bond orders (<1.5). Our results extend the list of possible carbon states at extreme conditions.

  • 18.
    Atthapak, C.
    et al.
    Chulalongkorn Univ, Thailand; Minist Higher Educ Sci Res & Innovat, Thailand.
    Ektarawong, A.
    Chulalongkorn Univ, Thailand; Minist Higher Educ Sci Res & Innovat, Thailand.
    Pakornchote, T.
    Chulalongkorn Univ, Thailand; Minist Higher Educ Sci Res & Innovat, Thailand.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Bovornratanaraks, T.
    Chulalongkorn Univ, Thailand; Minist Higher Educ Sci Res & Innovat, Thailand.
    Effect of atomic configuration and spin-orbit coupling on thermodynamic stability and electronic bandgap of monolayer 2H-Mo1-xWxS2 solid solutions2021In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 23, no 24, p. 13535-13543Article in journal (Refereed)
    Abstract [en]

    Through a combination of density functional theory calculations and cluster-expansion formalism, the effect of the configuration of the transition metal atoms and spin-orbit coupling on the thermodynamic stability and electronic bandgap of monolayer 2H-Mo1-xWxS2 is investigated. Our investigation reveals that, in spite of exhibiting a weak ordering tendency of Mo and W atoms at 0 K, monolayer 2H-Mo1-xWxS2 is thermodynamically stable as a single-phase random solid solution across the entire composition range at temperatures higher than 45 K. The spin-orbit coupling effect, induced mainly by W atoms, is found to have a minimal impact on the mixing thermodynamics of Mo and W atoms in monolayer 2H-Mo1-xWxS2; however, it significantly induces change in the electronic bandgap of the monolayer solid solution. We find that the band-gap energies of ordered and disordered solid solutions of monolayer 2H-Mo1-xWxS2 do not follow Vegards law. In addition, the degree of the SOC-induced change in band-gap energy of monolayer 2H-Mo1-xWxS2 solid solutions not only depends on the Mo and W contents, but for a given alloy composition it is also affected by the configuration of the Mo and W atoms. This poses a challenge of fine-tuning the bandgap of monolayer 2H-Mo1-xWxS2 in practice just by varying the contents of Mo and W.

  • 19.
    Azina, Clio
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tunca, Bensu
    Katholieke Univ Leuven, Belgium.
    Petruhins, Andrejs
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Xin, Binbin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Yildizhan Özyar, Melike
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Vleugels, Jozef
    Katholieke Univ Leuven, Belgium.
    Lambrinou, Konstantina
    SCK CEN, Belgium; Univ Huddersfield, England.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Deposition of MAX phase-containing thin films from a (Ti,Zr)(2)AlC compound target2021In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 551, article id 149370Article in journal (Refereed)
    Abstract [en]

    This work reports on sputter depositions carried out from a compound (Ti,Zr)(2)AlC target on Al2O3(0 0 0 1) substrates at temperatures ranging between 500 and 900 degrees C. Short deposition times yielded 30-40 nm-thick Al-containing (Ti,Zr)C films, whereas longer depositions yielded thicker films up to 90 nm which contained (Ti,Zr)C and intermetallics. At 900 degrees C, the longer depositions led to films that also consisted of solid solution MAX phases. Detailed transmission electron microscopy showed that both (Ti,Zr)(2)AlC and (Ti,Zr)(3)AlC2 solid solution MAX phases were formed. Moreover, this work discusses the growth mechanism of the thicker films, which started with the formation of the mixed (Ti,Zr)C carbide, followed by the nucleation and growth of aluminides, eventually leading to solid state diffusion of Al within the carbide, at the highest temperature (900 degrees C) to form the MAX phases.

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  • 20.
    Bagherzadeh, Peggy
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry.
    (1,3-di-tert-butyltriazenide) Cu(I) as vapor deposition precursor2023Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    In the past few decades, devices such as computers have become smaller, and their performance has improved beyond comparison. Semiconductors and interconnectors are used in almost all devices today and are made of thin films. Chemical vapor deposition (CVD) and atomic layer deposition (ALD) are common methods for depositing conformal films, where the film grows by being exposed to precursors either continuously as in CVD or by pulses as is pulsed CVD and ALD. It has been reported that Cu amidinate and guanidinate are precursors for depositing metallic Cu (Copper), but they tend to decompose. Precursors that are thermally stable and can be used to deposit a thin film of Cu are (1,3-di-tert-butyltriazenides) copper(I) (Cu-triazenides). This precursor has been synthesized and developed by the Pedersen Group in the Department of Physics, Chemistry, and Biology (IFM) at Linköpings University. This thesis investigates if Cu-triazenides are suitable as vapor deposition precursors using pulsed CVD and if Cu-triazenides are suitable as an ALD precursor with H2O as the second precursor. The main objective of this thesis is to focus on films deposited with ALD by finding the ALD window that gives a growth per cycle and making a saturation curve for each precursor. Si(100) and glass were used as the substrate, and SEM-EDX (Scanning electron microscopy- Energy- dispersive X-ray spectroscopy), XRD (X-ray diffraction), and XRR (X-ray reflectivity) analyzed the chemical, physical and, optical properties of the films. The Cu-triazenides were suitable as single-source precursors, as films were deposited with pulsed CVD on both Si(100) and glass. ALD deposited no film on Si(100) between the temperature 175–300 °C, and the analysis methods did not provide information on the thickness and composition of the films deposited on the glass.

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  • 21.
    Bairagi, Samiran
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Chang, Jui-Che
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tarntair, Fu-Gow
    National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan.
    Wu, Wan-Yu
    National United University, Miaoli, 36063, Taiwan.
    Gueorguiev, Gueorgui Kostov
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    de Almeida, Edward Ferraz
    Federal University of the West of Bahia, Brazil.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lin, Kun-Lin
    Taiwan Semiconductor Research Institute (TSRI), Taiwan.
    Hsu, Shao-Hui
    Taiwan Semiconductor Research Institute (TSRI), Taiwan.
    Shieh, Jia-Min
    Taiwan Semiconductor Research Institute (TSRI), Taiwan.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Horng, Ray-Hua
    National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Formation of quaternary Zn(AlxGa1−x)2O4 epilayers driven by thermally induced interdiffusion between spinel ZnGa2O4 epilayer and Al2O3 substrate2023In: Materials Today Advances, ISSN 2590-0498, Vol. 20, article id 100422Article in journal (Refereed)
    Abstract [en]

    Zinc aluminogallate, Zn(AlxGa1−x)2O4 (ZAGO), a single-phase spinel structure, offers considerable potential for high-performance electronic devices due to its expansive compositional miscibility range between aluminum (Al) and gallium (Ga). Direct growth of high-quality ZAGO epilayers however remains problematic due to the high volatility of zinc (Zn). This work highlights a novel synthesis process for high-quality epitaxial quaternary ZAGO thin films on sapphire substrates, achieved through thermal annealing of a ZnGa2O4 (ZGO) epilayer on sapphire in an ambient air setting. In-situ annealing x-ray diffraction measurements show that the incorporation of Al in the ZGO epilayer commenced at 850 °C. The Al content (x) in ZAGO epilayer gradually increased up to around 0.45 as the annealing temperature was raised to 1100 °C, which was confirmed by transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy. X-ray rocking curve measurement revealed a small full width at half maximum value of 0.72 °, indicating the crystal quality preservation of the ZAGO epilayer with a high Al content. However, an epitaxial intermediate �–(AlxGa1−x)2O3 layer (� - AGO) was formed between the ZAGO and sapphire substrate. This is believed to be a consequence of the interdiffusion of Al and Ga between the ZGO thin film and sapphire substrate. Using density functional theory, the substitution cost of Ga in sapphire was determined to be about 0.5 eV lower than substitution cost of Al in ZGO. Motivated by this energetically favorable substitution, a formation mechanism of the ZAGO and AGO layers was proposed. Spectroscopic ellipsometry studies revealed an increase in total thickness of the film from 105.07 nm (ZGO) to 147.97 nm (ZAGO/AGO) after annealing to 1100 °C, which were corroborated using TEM. Furthermore, an observed increase in the direct (indirect) optical bandgap from 5.06 eV (4.7 eV) to 5.72 eV (5.45 eV) with an increasing Al content in the ZAGO layer further underpins the formation of a quaternary ZAGO alloy with a tunable composition.

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  • 22.
    Bakhit, Babak
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Univ Cambridge, England; Univ Cambridge, England.
    Oxidation properties of quaternary Zr-based diboride thin films grown by hybrid high-power impulse/DC magnetron co-sputtering2024In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 42, no 1, article id 010401Article in journal (Other academic)
    Abstract [en]

    Sputter-deposited transition metal diborides are subject of increasing attention for protective hard coatings. However, they suffer from high brittleness and rapid oxidation. Alloying with Ta increases their toughness, but their oxidation resistance requires further enhancement. Here, the influence of adding Si on the microstructure, mechanical, and oxidation properties of quaternary Zr1-(x + y)TaxSiyBz thin films grown by hybrid high-power impulse/DC magnetron co-sputtering (ZrB2-DCMS/Ta-HiPIMS/Si-DCMS) is studied. The layers are deposited at two different conditions of Ta-target HiPIMS powers and frequencies (30 W/100 Hz and 60 W/200 Hz series) with Si-target DCMS powers P-Si = 0, 10, 15, and 20 W, while the ZrB2-target DCMS power is maintained constant at 200 W. For the 30 W/100 Hz series, x decreases from 0.20 to 0.15, y increases from 0 to 0.22, and z decreases from 2.0 to 1.8 by increasing P-Si. The Ta/metal ratio remains constant at x = 0.3 for the 60 W/200 Hz series, while y increases from 0 to 0.1, and z decreases from 1.7 to 1.4. All layers show columnar growth and crystallize in a hexagonal-diboride structure, but crystal orientations change by increasing P-Si. The 60 W/200 Hz series have much denser microstructure than the 30 W/100 Hz series. The 60 W/200 Hz series have high hardness values (>= 35 GPa), while the hardness of the 30 W/100 Hz series significantly decreases from similar to 37 to similar to 21 GPa as a function of P-Si. Zr0.7Ta0.3B1.7 has markedly better high-temperature oxidation resistance than Zr0.8Ta0.2B2.0 due to the formation of protective B-containing oxide scales. Alloying with Si considerably decreases the oxidation rate of the 30 W/100 Hz series owing to the formation of oxide scales containing a ZrSiO4 phase with a thin Si oxide top layer; however, the oxidation rate increases for the 60 W/200 Hz series as these quaternary alloys do not contain sufficiently high B and Si to form oxidation protective barriers.

  • 23.
    Bakhit, Babak
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Dorri, Samira
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kooijman, Agnieszka
    Department of Materials Science and Engineering, Delft University of Technology, Delft, the Netherlands.
    Wu, Zhengtao
    School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, China.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Mol, Johannes M.C.
    Department of Materials Science and Engineering, Delft University of Technology, Delft, the Netherlands.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petrov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Materials Research Laboratory and Department of Materials Science, University of Illinois, Urbana, IL, USA; Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan .
    Greene, Joseph E
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Materials Research Laboratory and Department of Materials Science, University of Illinois, Urbana, IL, USA; Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan .
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Multifunctional ZrB2-rich Zr1-xCrxBy thin films with enhanced mechanical, oxidation, and corrosion properties2021In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 185, article id 109990Article in journal (Refereed)
    Abstract [en]

    Refractory transition-metal (TM) diborides have high melting points, excellent hardness, and good  chemical  stability.  However, these properties are not sufficient for applications involving extreme  environments that require high mechanical strength as well as oxidation and corrosion resistance. Here, we study the effect of Cr addition on the properties of ZrB2-rich Zr1-xCrxBy thin films grown by hybrid high-power impulse and dc magnetron co-sputtering (Cr-HiPIMS/ZrB2-DCMS) with a 100-V Cr-metal-ion synchronized potential. Cr metal fraction, x = Cr/(Zr+Cr), is increased from 0.23 to 0.44 by decreasing the power Pzrb2 applied to the DCMS ZrB2 target from 4000 to 2000 W, while the average power, pulse width, and frequency applied to the HiPIMS Cr target are maintained constant. In addition, y decreases from 2.18 to 1.11 as a function of Pzrb2, as a result of supplying Cr to the growing film and preferential B resputtering caused by the pulsed Cr-ion flux. ZrB2.18, Zr0.77Cr0.23B1.52, Zr0.71Cr0.29B1.42, and Zr0.68Cr0.32B1.38 2 films have hexagonal AlB2 crystal structure with a columnar nanostructure, while Zr0.64Cr0.36B1.30 and Zr0.56Cr0.44B1.11 are  amorphous. All films show hardness above 30 GPa. Zr0.56Cr0.44B1.11 alloys exhibit much better toughness, wear, oxidation, and corrosion resistance than ZrB2.18. This combination of properties   makes Zr0.56Cr0.44B1.11 ideal candidates for numerous strategic applications.

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  • 24.
    Bakhit, Babak
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Engberg, David
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petrov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Univ Illinois, IL 61801 USA.
    Greene, Joseph E
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Univ Illinois, IL 61801 USA.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1-xTaxBy thin films2019In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, no 3, article id 031506Article in journal (Refereed)
    Abstract [en]

    Refractory transition-metal diborides exhibit inherent hardness. However, this is not always sufficient to prevent failure in applications involving high mechanical and thermal stress, since hardness is typically accompanied by brittleness leading to crack formation and propagation. Toughness, the combination of hardness and ductility, is required to avoid brittle fracture. Here, the authors demonstrate a strategy for simultaneously enhancing both hardness and ductility of ZrB2-rich thin films grown in pure Ar on Al2O3(0001) and Si(001) substrates at 475 degrees C. ZrB2.4 layers are deposited by dc magnetron sputtering (DCMS) from a ZrB2 target, while Zr1-xTaxBy alloy films are grown, thus varying the B/metal ratio as a function of x, by adding pulsed high-power impulse magnetron sputtering (HiPIMS) from a Ta target to deposit Zr1-xTaxBy alloy films using hybrid Ta-HiPIMS/ZrB2-DCMS sputtering with a substrate bias synchronized to the metal-rich portion of each HiPIMS pulse. The average power P-Ta (and pulse frequency) applied to the HiPIMS Ta target is varied from 0 to 1800W (0 to 300 Hz) in increments of 600W (100 Hz). The resulting boron-to-metal ratio, y = B/(Zr+Ta), in as-deposited Zr1-xTaxBy films decreases from 2.4 to 1.5 as P-Ta is increased from 0 to 1800W, while x increases from 0 to 0.3. A combination of x-ray diffraction (XRD), glancing-angle XRD, transmission electron microscopy (TEM), analytical Z-contrast scanning TEM, electron energy-loss spectroscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and atom-probe tomography reveals that all films have the hexagonal AlB2 crystal structure with a columnar nanostructure, in which the column boundaries of layers with 0 amp;lt;= x amp;lt; 0.2 are B-rich, whereas those with x amp;gt;= 0.2 are Ta-rich. The nanostructural transition, combined with changes in average column widths, results in an similar to 20% increase in hardness, from 35 to 42 GPa, with a simultaneous increase of similar to 30% in nanoindentation toughness, from 4.0 to 5.2MPa root m. Published by the AVS.

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  • 25.
    Baldinozzi, Gianguido
    et al.
    Univ Paris Saclay, France.
    Casillas Trujillo, Luis
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Patel, Maulik K.
    Univ Liverpool, England.
    Sickafus, Kurt E.
    Univ Tennessee, TN 37996 USA.
    Structural complexity of Y6BO12 fluorite-related ternary oxides2021In: MRS Advances, E-ISSN 2059-8521, Vol. 6, no 4-5, p. 107-111Article in journal (Refereed)
    Abstract [en]

    Oxides with generic stoichiometry M7O12 occupy, in a generic phase diagram, an intermediate place between fluorite and bixbyite structure types. Their structure is derived from the ideal fluorite structure, and it is characterized by a more or less pronounced ordering of the O vacancies within the average fluorite sublattice. We believe that ternary oxides with this kind of formula provide interesting degrees of flexibility for understanding the structural characteristic of these structures in the context of fission product stabilization in nuclear fuels and in the field of actinide waste forms as well. We would like to discuss the structural characteristics of the chemical bonds in ternary systems consisting of trivalent and hexavalent cations. Eventually, in compounds with generic formula Y6B+6O12, the B cation can be either a transition metal (W, Mo) or hexavalent uranium. We believe that studying the polyhedron of the sevenfold coordinated Y ion is particularly interesting to understand the flexibility of the chemical bonds: it is often described in the literature as a mono-capped trigonal prism, with bond lengths exhibiting an extremely large dispersion, ranging for instance from 2.19 to 2.70 angstrom in Y6WO12. We would discuss the implications of this large dispersion of distances on the chemical bond characteristics and compare DFT models with established experimental knowledge on pristine and irradiated specimens. Graphic abstract

  • 26.
    Banyai, Istvan
    et al.
    University of Debrecen UD, Hungary.
    Farkas, Ildiko
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Toth, Imre
    University of Debrecen UD, Hungary.
    Simple O-17 NMR method for studying electron self-exchange reaction between UO22+ and U4+ aqua ions in acidic solution2016In: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 54, no 6, p. 444-450Article in journal (Refereed)
    Abstract [en]

    O-17 NMR spectroscopy is proven to be suitable and convenient method for studying the electron exchange by following the decrease of O-17-enrichment in (UOO2+)-O-17 ion in the presence of U4+ ion in aqueous solution. The reactions have been performed at room temperature using I=5MClO(4)(-) ionic medium in acidic solutions in order to determine the kinetics of electron exchange between the U4+ and UO22+ aqua ions. The rate equation is given as R = a[H+](-2) + R, where R is an acid independent parallel path. R depends on the concentration of the uranium species according to the following empirical rate equation: R = k(1)[UO2+](1/2)[U4+](1/2) + k(2)[UO2+](3/2)[U4+](1/2). The mechanism of the inverse H+ concentration-dependent path is interpreted as equilibrium formation of reactive UO2+ species from UO22+ and U4+ aqua ions and its electron exchange with UO22+. The determined rate constant of this reaction path is in agreement with the rate constant of UO22+-UO2+, one electron exchange step calculated by Marcus theory, match the range given experimentally of it in an early study. Our value lies in the same order of magnitude as the recently calculated ones by quantum chemical methods. The acid independent part is attributed to the formation of less hydrolyzed U(V) species, i.e. UO3+, which loses enrichment mainly by electron exchange with UO22+ ions. One can also conclude that O-17 NMR spectroscopy, or in general NMR spectroscopy with careful kinetic analysis, is a powerful tool for studying isotope exchange reactions without the use of sophisticated separation processes. Copyright (C) 2015 John Wiley amp; Sons, Ltd.

  • 27.
    Bentzel, Grady W.
    et al.
    Drexel University, PA 19104 USA.
    Naguib, Michael
    Drexel University, PA 19104 USA.
    Lane, Nina J.
    Drexel University, PA 19104 USA.
    Vogel, Sven C.
    Los Alamos National Lab, NM 87545 USA.
    Presser, Volker
    Drexel University, PA 19104 USA.
    Dubois, Sylvain
    University of Poitiers, France.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barsoum, Michel W.
    Drexel University, PA 19104 USA.
    Caspi, Elad N.
    Drexel University, PA 19104 USA; Nucl Research Centre Negev, Israel.
    High-Temperature Neutron Diffraction, Raman Spectroscopy, and First-Principles Calculations of Ti3SnC2 and Ti2SnC2016In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 99, no 7, p. 2233-2242Article in journal (Refereed)
    Abstract [en]

    Herein, we report-for the first time-on the additive-free bulk synthesis of Ti3SnC2. A detailed experimental study of the structure of the latter together with a secondary phase, Ti2SnC, is presented through the use of X-ray diffraction (XRD), and high-resolution transmission microscopy (HRTEM). A previous sample of Ti3SnC2, made using Fe as an additive and Ti2SnC as a secondary phase, was studied by high-temperature neutron diffraction (HTND) and XRD. The room-temperature crystallographic parameters of the two MAX phases in the two samples are quite similar. Based on Rietveld analysis of the HTND data, the average linear thermal expansion coefficients of Ti3SnC2 in the a and c directions were found to be 8.5 (2).10(-6) K-1 and 8.9 (1) . 10(-6) K-1, respectively. The respective values for the Ti2SnC phase are 10.1 (3) . 10(-6) K-1 and 10.8 (6) . 10(-6) K-1. Unlike other MAX phases, the atomic displacement parameters of the Sn atoms in Ti3SnC2 are comparable to those of the Ti and C atoms. When the predictions of the atomic displacement parameters obtained from density functional theory are compared to the experimental results, good quantitative agreement is found for the Sn atoms. In the case of the Ti and C atoms, the agreement is more qualitative. We also used first principles to calculate the elastic properties of both Ti2SnC and Ti3SnC2 and their Raman active modes. The latter are compared to experiment and the agreement was found to be good.

  • 28.
    Beshkova, M.
    et al.
    Bulgarian Acad Sci, Bulgaria.
    Blagoev, B. S.
    Bulgarian Acad Sci, Bulgaria.
    Mehandzhiev, V
    Bulgarian Acad Sci, Bulgaria.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Georgieva, B.
    Bulgarian Acad Sci, Bulgaria.
    Avramova, I
    Bulgarian Acad Sci, Bulgaria.
    Terziyska, P.
    Bulgarian Acad Sci, Bulgaria.
    Kovacheva, D.
    Bulgarian Acad Sci, Bulgaria.
    Strijkova, V
    Bulgarian Acad Sci, Bulgaria.
    Initial conditions for preparation of thin AlN films by atomic layer deposition2020In: 21ST INTERNATIONAL SUMMER SCHOOL ON VACUUM, ELECTRON AND ION TECHNOLOGIES, IOP PUBLISHING LTD , 2020, Vol. 1492, article id 012021Conference paper (Refereed)
    Abstract [en]

    Thin AlN films were grown on Si substrates in a Beneq TFS-200 ALD reactor. The atomic layer deposition (ALD) process consisted of two half cycles - aluminum adsorption and nitridization separated by a purging step. TMA (trimethylaluminum) and NH3 were used as precursors, and nitrogen (N-2), as a carrier gas. The pulse duration, purging time, deposition temperature and other deposition conditions were varied to obtain AlN films with desired properties. The X-ray diffraction (XRD) data showed that the AlN films had an amorphous character. The films chemical composition and bonding states were investigated by X-ray photoelectron spectroscopy. The high resolution Al 2p and N 1s spectra confirmed the presence of AlN with peaks located at 74.1 eV and 397.7 eV, respectively, for all layers.

  • 29.
    Beshkova, M.
    et al.
    Bulgarian Acad Sci, Bulgaria.
    Deminskyi, Petro
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Atomic layer deposition of AlN using trimethylaluminium and ammonia2020In: 21ST INTERNATIONAL SUMMER SCHOOL ON VACUUM, ELECTRON AND ION TECHNOLOGIES, IOP PUBLISHING LTD , 2020, Vol. 1492, article id 012046Conference paper (Refereed)
    Abstract [en]

    Thin AlN films were grown in a Picosun R-200 atomic layer deposition (ALD) reactor on Si substrates. Trimethylaluminium (TMA) and NH3 were used as precursors; the substrates were cleaned in-situ by H-2 and N-2 plasma. The surface morphology of the films grown was studied in the temperature range 350 - 450 degrees C. The films crystalline structure was investigated by grazing incidence X-ray diffraction. The AN films were polycrystalline with a hexagonal wurtzite structure regardless of the substrate temperature. The results of scanning electron microscopy (SEM) revealed nanometer-sized crystallites, with the size increasing from 10 nm to 30 nm as the deposition temperature was increased. The results are promising in view of further studies of the properties of thin AN films.

  • 30.
    Beshkova, Milena
    et al.
    Bulgarian Acad Sci, Bulgaria.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Properties and potential applications of two-dimensional AlN2020In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 176Article, review/survey (Refereed)
    Abstract [en]

    The success of Graphene has triggered the research interest in other stable, single and few-atom-thick layers of van der Waals materials, which can possess attractive and technologically useful properties. Other complex structures, such as boron nitride, MXenes and metal chalcogenides have been successfully synthesized as layered materials showing advanced properties. Here, after an introduction briefing novel 2D materials, we focus on 2D AlN and present a review covering theoretical considerations on the stability of an infinite hexagonal AlN (h-AlN) sheet, differences that occur in the electronic structure between bulk AlN and single layer and discuss possible methods of tuning their electronic and magnetic properties by manipulating the surface and strain using DFT (density functional theory) computations. We address potential applications of 2D-AlN with an emphasis on gas sensing for CO2, CO, H-2, O-2, NO and NO2 in the presence of NH3. Further, we discuss some growth strategies of AlN single layer and few layers on different substrates. 2D AlN layers and nanotubes with ultrawide bandgap (9.20-9.60 eV) which shows a great potential to support innovative and front-end development of deep-ultraviolet optoelectronic devices are illustrated.

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  • 31.
    Biradar, Bhimaraya R.
    et al.
    Natl Inst Technol Karnataka, India.
    Maity, Sukanya
    Linköping University, Department of Physics, Chemistry and Biology, Materials design. Linköping University, Faculty of Science & Engineering. Natl Inst Technol Karnataka, India.
    Chandewar, Pranay R.
    Indian Inst Technol Hyderabad, India.
    Shee, Debaprasad
    Indian Inst Technol Hyderabad, India.
    Das, Partha Pratim
    Natl Inst Technol Karnataka, India.
    Mal, Sib Sankar
    Natl Inst Technol Karnataka, India.
    High areal capacitance polyoxotungstate-reduced graphene oxide-based supercapacitors2023In: Inorganic Chemistry Communications, ISSN 1387-7003, E-ISSN 1879-0259, Vol. 155, article id 110987Article in journal (Refereed)
    Abstract [en]

    The modern lifestyle has driven the advent of high-power electronic gadgets to need high-efficiency energy storage devices. Towards that goal, reduced graphene oxide (rGO) mediated polyoxometalates (POMs) based electrode materials are increasingly showing promising performance for building efficient energy storage devices primarily due to their redox properties. In this report, the silicotungstate [K5[SiVW11O40]. nH2O (SiVW11) embedded rGO nanocomposites as electrode materials in supercapacitor applications were synthesized via chemical and hydrothermal methods. The synthesized nanocomposites were characterized by various techniques, such as Fourier-Transform-Infrared (FTIR) Spectroscopy, Powder X-ray Diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS), Thermogravimetric Analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) measurement. The nanocomposites electrochemical properties were examined by adopting a two-electrode setup with cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) in a 0.5 M H2SO4 electrolyte medium. The hydrothermally reduced graphene oxide (HrGO) nanocomposite exhibited a noticeable surge in areal capacitance of 377.4 mF/cm2 at a current density of 1.5 mA/cm2. The resulting composite had 52.4 & mu;Wh/cm2 and 1500 & mu;W/cm2 as energy and power density, respectively at 1.5 mA/cm2 current density. In addition, the capacitance retention is over 81% after 5000 cycles at a current density of 9 mA/ cm2. The highest specific power of 5000 & mu;W/cm2 was obtained at 5 mA/cm2 current density. On the other hand, chemically reduced graphene (CrGO) nanocomposite showed an areal capacitance of 277.2 mF/cm2 at the same current density. As a result, the SiVW11 clusters coupled with the rGO increase the areal capacitance of nanocomposites with exceptional electrical and mechanical stability. From an application standpoint, both composites were employed successfully for running a DC motor in a series cell connection.

  • 32.
    Bruening, Lukas
    et al.
    Univ Cologne, Germany.
    Jena, Nityasagar
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Bykova, Elena
    Goethe Univ Frankfurt, Germany.
    Jurzick, Pascal L.
    Univ Cologne, Germany.
    Flosbach, Niko T.
    Univ Cologne, Germany.
    Mezouar, Mohamed
    European Synchrotron Radiat Facil, France.
    Hanfland, Michael
    European Synchrotron Radiat Facil, France.
    Giordano, Nico
    Deutsch Elektronen Synchrotron DESY, Germany.
    Fedotenko, Timofey
    Deutsch Elektronen Synchrotron DESY, Germany.
    Winkler, Bjoern
    Goethe Univ Frankfurt, Germany.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Bykov, Maxim
    Univ Cologne, Germany.
    Stabilization of Guanidinate Anions [CN3]5− in Calcite-Type SbCN32023In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773Article in journal (Refereed)
    Abstract [en]

    The stabilization of nitrogen-rich phases presents a significant chemical challenge due to the inherent stability of the dinitrogen molecule. This stabilization can be achieved by utilizing strong covalent bonds in complex anions with carbon, such as cyanide CN- and NCN(2- )carbodiimide, while more nitrogen-rich carbonitrides are hitherto unknown. Following a rational chemical design approach, we synthesized antimony guanidinate SbCN3 at pressures of 32-38 GPa using various synthetic routes in laser-heated diamond anvil cells. SbCN3, which is isostructural to calcite CaCO3, can be recovered under ambient conditions. Its structure contains the previously elusive guanidinate anion [CN3](5-), marking a fundamental milestone in carbonitride chemistry. The crystal structure of SbCN3 was solved and refined from synchrotron single-crystal X-ray diffraction data and was fully corroborated by theoretical calculations, which also predict that SbCN3 has a direct band gap with the value of 2.20 eV. This study opens a straightforward route to the entire new family of inorganic nitridocarbonates.

  • 33.
    Buttera, Sydney C.
    et al.
    Carleton University, Canada.
    Ronnby, Karl
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Chemistry.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Ojamäe, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Barry, Sean T.
    Carleton University, Canada.
    Thermal study of an indium trisguanidinate as a possible indium nitride precursor2018In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 36, no 1, article id 01A101Article in journal (Refereed)
    Abstract [en]

    Tris-N,N,-dimethyl-N,N -diisopropylguanidinatoindium(III) has been investigated both as a chemical vapor deposition precursor and an atomic layer deposition precursor. Although deposition was satisfactory in both cases, each report showed some anomalies in the thermal stability of this compound, warrenting further investigation, which is reported herein. The compound was found to decompose to produce diisopropylcarbodiimide both by computational modeling and solution phase nuclear magnetic resonance characterization. The decomposition was shown to have an onset at approximately 120 degrees C and had a constant rate of decomposition from 150 to 180 degrees C. The ultimate decomposition product was suspected to be bisdimethylamidoN, N,-dimethyl-N,N -diisopropylguanidinato-indium(III), which appeared to be an intractable, nonvolatile polymer. Published by the AVS.

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  • 34.
    Buttera, Sydney C.
    et al.
    Carleton Univ, Canada.
    Rouf, Polla
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Deminskyi, Petro
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    O´brien, Nathan
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Barry, Sean T.
    Carleton Univ, Canada.
    Resolving Impurities in Atomic Layer Deposited Aluminum Nitride through Low Cost, High Efficiency Precursor Design2021In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 60, no 15, p. 11025-11031Article in journal (Refereed)
    Abstract [en]

    A heteroleptic amidoalane precursor is presented as a more suitably designed candidate to replace trimethylaluminum (TMA) for atomic layer deposition of aluminum nitride (AlN). The lack of C-Al bonds and the strongly reducing hydride ligands in [AlH2(NMe2)](3) (1) were specifically chosen to limit impurities in target aluminum nitride (AlN) films. Compound 1 is made in a high yield, scalable synthesis involving lithium aluminum hydride and dimethylammonium chloride. It has a vapor pressure of 1 Torr at 40 degrees C and evaporates with negligible residual mass in thermogravimetric experiments. Ammonia (NH3) plasma and 1 in an atomic layer deposition (ALD) process produced crystalline AlN films above 200 degrees C with an Al:N ratio of 1.04. Carbon and oxygen impurities in resultant AlN films were reduced to <1% and <2%, respectively. By using a precursor with a rational and advantageous design, we can improve the material quality of AlN films compared to those deposited using the industrial standard trimethylaluminum and could reduce material cost by up to 2 orders of magnitude.

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  • 35.
    Bykov, Maxim
    et al.
    Univ Bayreuth, Germany.
    Bykova, Elena
    Deutsch Elektronen Synchrotron DESY, Germany.
    Koemets, Egor
    Univ Bayreuth, Germany.
    Fedotenko, Timofey
    Univ Bayreuth, Germany.
    Aprilis, Georgios
    Univ Bayreuth, Germany.
    Glazyrin, Konstantin
    Deutsch Elektronen Synchrotron DESY, Germany.
    Liermann, Hanns-Peter
    Deutsch Elektronen Synchrotron DESY, Germany.
    Ponomareva, Alena V.
    Natl Univ Sci and Technol MISIS, Russia.
    Tidholm, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Tasnadi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor A.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Dubrovinskaia, Natalia
    Univ Bayreuth, Germany.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    High-Pressure Synthesis of a Nitrogen-Rich Inclusion Compound ReN8·xN2 with Conjugated Polymeric Nitrogen Chains2018In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 57, no 29, p. 9048-9053Article in journal (Refereed)
    Abstract [en]

    A nitrogen-rich compound, ReN(8)xN(2), was synthesized by a direct reaction between rhenium and nitrogen at high pressure and high temperature in a laser-heated diamond anvil cell. Single-crystal X-ray diffraction revealed that the crystal structure, which is based on the ReN8 framework, has rectangular-shaped channels that accommodate nitrogen molecules. Thus, despite a very high synthesis pressure, exceeding 100GPa, ReN(8)xN(2) is an inclusion compound. The amount of trapped nitrogen (x) depends on the synthesis conditions. The polydiazenediyl chains [-N=N-] that constitute the framework have not been previously observed in any compound. Abinitio calculations on ReN(8)xN(2) provide strong support for the experimental results and conclusions.

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  • 36.
    Bykov, Maxim
    et al.
    Carnegie Inst Sci, DC 20015 USA; Howard Univ, DC 20059 USA.
    Fedotenko, Timofey
    Univ Bayreuth, Germany.
    Chariton, Stella
    Univ Chicago, IL 60637 USA.
    Laniel, Dominique
    Univ Bayreuth, Germany.
    Glazyrin, Konstantin
    Deutsch Electronen Synchrotron DESY, Germany.
    Hanfland, Michael
    European Synchrotron Radiat Facil, France.
    Smith, Jesse S.
    Argonne Natl Lab, IL 60439 USA.
    Prakapenka, Vitali B.
    Univ Chicago, IL 60637 USA.
    Mahmood, Mohammad F.
    Howard Univ, DC 20059 USA.
    Goncharov, Alexander F.
    Carnegie Inst Sci, DC 20015 USA.
    Ponomareva, Alena V
    Natl Univ Sci & Technol MISIS, Russia.
    Tasnadi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Abrikossov, Alexei
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Masood, Talha Bin
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Hotz, Ingrid
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Rudenko, Alexander N.
    Wuhan Univ, Peoples R China; Wuhan Univ, Peoples R China; Radboud Univ Nijmegen, Netherlands; Ural Fed Univ, Russia.
    Katsnelson, Mikhail I
    Radboud Univ Nijmegen, Netherlands; Ural Fed Univ, Russia.
    Doubrovinckaia, Natalia
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Univ Bayreuth, Germany.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    High-Pressure Synthesis of Dirac Materials: Layered van der Waals Bonded BeN4 Polymorph2021In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 126, no 17, article id 175501Article in journal (Refereed)
    Abstract [en]

    High-pressure chemistry is known to inspire the creation of unexpected new classes of compounds with exceptional properties. Here, we employ the laser-heated diamond anvil cell technique for synthesis of a Dirac material BeN4. A triclinic phase of beryllium tetranitride tr-BeN4 was synthesized from elements at similar to 85 GPa. Upon decompression to ambient conditions, it transforms into a compound with atomic-thick BeN4 layers interconnected via weak van der Waals bonds and consisting of polyacetylene-like nitrogen chains with conjugated pi systems and Be atoms in square-planar coordination. Theoretical calculations for a single BeN4 layer show that its electronic lattice is described by a slightly distorted honeycomb structure reminiscent of the graphene lattice and the presence of Dirac points in the electronic band structure at the Fermi level. The BeN4 layer, i.e., beryllonitrene, represents a qualitatively new class of 2D materials that can be built of a metal atom and polymeric nitrogen chains and host anisotropic Dirac fermions.

  • 37.
    Bykova, Elena
    et al.
    Carnegie Inst Sci, DC 20015 USA; Univ Bayreuth, Germany.
    Johansson, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Bykov, Maxim
    Carnegie Inst Sci, DC 20015 USA; Univ Cologne, Germany.
    Chariton, Stella
    Univ Chicago, IL 60637 USA.
    Fei, Hongzhan
    Univ Bayreuth, Germany.
    Ovsyannikov, Sergey V.
    Univ Bayreuth, Germany.
    Aslandukova, Alena
    Univ Bayreuth, Germany.
    Gabel, Stefan
    Friedrich Alexander Univ Erlangen Nurnberg, Germany.
    Holz, Hendrik
    Friedrich Alexander Univ Erlangen Nurnberg, Germany; Univ Kassel, Germany.
    Merle, Benoit
    Friedrich Alexander Univ Erlangen Nurnberg, Germany; Univ Kassel, Germany.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor A.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Smith, Jesse S.
    Argonne Natl Lab, IL 60439 USA.
    Prakapenka, Vitali B.
    Univ Chicago, IL 60637 USA.
    Katsura, Tomoo
    Univ Bayreuth, Germany.
    Doubrovinckaia, Natalia
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Univ Bayreuth, Germany.
    Goncharov, Alexander F.
    Carnegie Inst Sci, DC 20015 USA.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    Novel Class of Rhenium Borides Based on Hexagonal Boron Networks Interconnected by Short B-2 Dumbbells2022In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 34, no 18, p. 8138-8152Article in journal (Refereed)
    Abstract [en]

    Transition metal borides are known due to their attractive mechanical, electronic, refractive, and other properties. A new class of rhenium borides was identified by synchrotron single-crystal X-ray diffraction experiments in laser-heated diamond anvil cells between 26 and 75 GPa. Recoverable to ambient conditions, compounds rhenium triboride (ReB3) and rhenium tetraboride (ReB4) consist of close-packed single layers of rhenium atoms alternating with boron networks built from puckered hexagonal layers, which link short bonded (similar to 1.7 angstrom) axially oriented B-2 dumbbells. The short and incompressible Re-B and B-B bonds oriented along the hexagonal c-axis contribute to low axial compressibility comparable with the linear compressibility of diamond. Sub-millimeter samples of ReB3 and ReB4 were synthesized in a large-volume press at pressures as low as 33 GPa and used for material characterization. Crystals of both compounds are metallic and hard (Vickers hardness, H-V = 34(3) GPa). Geometrical, crystal-chemical, and theoretical analysis considerations suggest that potential ReBx compounds with x > 4 can be based on the same principle of structural organization as in ReB3 and ReB4 and possess similar mechanical and electronic properties.

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  • 38.
    Cabioch, Thierry
    et al.
    University of Poitiers, France.
    Alkazaz, Malaz
    University of Poitiers, France.
    Beaufort, Marie-France
    University of Poitiers, France.
    Nicolai, Julien
    University of Poitiers, France.
    Eyidi, Dominique
    University of Poitiers, France.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. University of Poitiers, France.
    Ti2AlN thin films synthesized by annealing of (Ti plus Al)/AlN multilayers2016In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 80, p. 58-63Article in journal (Refereed)
    Abstract [en]

    Single-phase Ti2AlN thin films were obtained by annealing in vacuum of (Ti + Al)/AIN multilayers deposited at room temperature by magnetron sputtering onto single-crystalline (0001) 4H-SiC and (0001) Al2O3 substrates. In-situ X-ray diffraction experiments combined with ex-situ cross-sectional transmission electron microscopy observations reveal that interdiffusion processes occur in the multilayer at a temperature of similar to 400 degrees C leading to the formation of a (Ti, Al, N) solid solution, having the hexagonal structure of alpha-Ti, whereas the formation of Ti2AlN occurs at 550-600 degrees C. Highly oriented (0002) Ti2AlN thin films can be obtained after an annealing at 750 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.

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  • 39.
    Calamba, Katherine
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Univ Lorraine, France.
    Barrirero, Jenifer
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Saarland Univ, Germany.
    Joesaar, M. P. Johansson
    SECO Tools AB, Sweden.
    Bruyere, S.
    Univ Lorraine, France.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Pierson, J. F.
    Univ Lorraine, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Muecklich, F.
    Saarland Univ, Germany.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Growth and high temperature decomposition of epitaxial metastable wurtzite (Ti1-x,Al-x)N(0001) thin films2019In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 688, article id 137414Article in journal (Refereed)
    Abstract [en]

    The structure, growth, and phase stability of (Ti1-x,Al-x)N films with high Al content were investigated. (Ti1-x,Al-x)N (x= 0.63 and 0.77) thin films were grown on MgO (111) substrates at 700 degrees C using a UHV DC magnetron sputtering system. The (Ti-0.37,Al-0.63)N film is a single crystal with a cubic NaCl (B1) structure while the (T-i0.23,Al-0.77)N film only shows epitaxial growth of the same cubic phase in the first few atomic layers. With increasing film thickness, epitaxial wurtzite (B4) forms. The thin cubic layer and the wurtzite film has an orientation relationship of c-(Ti-0.23,Al-0.77)N(111)[110]parallel to w-(Ti-0.23,Al-0.77)N(0001)[11 (2) over bar0]. Continued deposition results in a gradual break-down of the epitaxial growth. It is replaced by polycrystalline growth of wurtzite columns with a high degree of 0001 texture, separated by a Tienriched cubic phase. In the as-deposited state, c-(Ti-0.27,Al-0.63)N displays a homogeneous chemical distribution while the w-(Ti-0.23,Al-0.77)N has segregated to Al- and Ti-rich domains. Annealing at 900 degrees C resulted in the spinodal decomposition of the metastable c-(Ti-0.27,Al-0.63)N film and formation of coherent elongated c-AlN and cTi-N-rich domains with an average width of 4.5 +/- 0.2 nm while the width of the domains in the w-(Ti-0.23,Al-0.77)N film only marginally increases to 2.8 +/- 0.1 nm. The slower coarsening rate of the wurtzite structure compared to cubic is indicative of a higher thermal stability.

  • 40.
    Calamba, Katherine
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Univ Lorraine, France.
    Pierson, J. F.
    Univ Lorraine, France.
    Bruyere, S.
    Univ Lorraine, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barrirero, Jenifer
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Saarland Univ, Germany.
    Muecklich, F.
    Saarland Univ, Germany.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Jöesaar Johansson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. SECO Tools AB, Sweden.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Dislocation structure and microstrain evolution during spinodal decomposition of reactive magnetron sputtered heteroepixatial c-(Ti-0.37,Al-0.63)N/c-TiN films grown on MgO(001) and (111) substrates2019In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 125, no 10, article id 105301Article in journal (Refereed)
    Abstract [en]

    Heteroepitaxial c-(Ti-0.37,Al-0.63)N thin films were grown on MgO(001) and MgO(111) substrates using reactive magnetron sputtering. High resolution high-angle annular dark-field scanning transmission electron micrographs show coherency between the film and the substrate. In the as-deposited state, x-ray diffraction reciprocal space maps show a strained epitaxial film. Corresponding geometric phase analysis (GPA) deformation maps show a high stress in the film. At elevated temperature (900 degrees C), the films decompose to form iso-structural coherent c-Al- and c-TiN-rich domains, elongated along the elastically soft amp;lt;100amp;gt; directions. GPA analysis reveals that the c-TiN domains accommodate more dislocations than the c-AlN domains. This is because of the stronger directionality of the covalent bonds in c-AlN compared with c-TiN, making it more favorable for the dislocations to accumulate in c-TiN. The defect structure and strain generation in c-(Ti,Al)N during spinodal decomposition is affected by the chemical bonding state and elastic properties of the segregated domains.

  • 41.
    Cao, Nan
    et al.
    Tech Univ Munich, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Materials design. Linköping University, Faculty of Science & Engineering.
    Corral-Rascon, Eduardo
    Tech Univ Munich, Germany.
    Chen, Zhi
    Karlsruhe Inst Technol, Germany; Shenzhen Univ, Peoples R China.
    Ruben, Mario
    Karlsruhe Inst Technol, Germany; Univ Strasbourg, France; Karlsruhe Inst Technol, Germany.
    Senge, Mathias O.
    Tech Univ Munich, Germany.
    Barth, Johannes V.
    Tech Univ Munich, Germany.
    Riss, Alexander
    Tech Univ Munich, Germany.
    The role of aromaticity in the cyclization and polymerization of alkyne-substituted porphyrins on Au(111)2023In: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349Article in journal (Refereed)
    Abstract [en]

    Aromaticity is an established and widely used concept for the prediction of the reactivity of organic molecules. However, its role remains largely unexplored in on-surface chemistry, where the interaction with the substrate can alter the electronic and geometric structure of the adsorbates. Here we investigate how aromaticity affects the reactivity of alkyne-substituted porphyrin molecules in cyclization and coupling reactions on a Au(111) surface. We examine and quantify the regioselectivity in the reactions by scanning tunnelling microscopy and bond-resolved atomic force microscopy at the single-molecule level. Our experiments show a substantially lower reactivity of carbon atoms that are stabilized by the aromatic diaza[18]annulene pathway of free-base porphyrins. The results are corroborated by density functional theory calculations, which show a direct correlation between aromaticity and thermodynamic stability of the reaction products. These insights are helpful to understand, and in turn design, reactions with aromatic species in on-surface chemistry and heterogeneous catalysis. While aromaticity is a useful concept for assessing the reactivity of organic compounds, the connection between aromaticity and on-surface chemistry remains largely unexplored. Now, scanning probe experiments on cyclization reactions of porphyrins on Au(111) show that the peripheral carbon atoms outside of the aromatic 18-& pi; electron pathway exhibit a higher reactivity.

  • 42.
    Carlsson, Adam
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials design. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Materials design. Linköping University, Faculty of Science & Engineering.
    Dahlqvist, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Materials design. Linköping University, Faculty of Science & Engineering.
    Theoretical predictions of phase stability for orthorhombic and hexagonal ternary MAB phases2022In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 24, no 18, p. 11249-11258Article in journal (Refereed)
    Abstract [en]

    In the quest for finding novel thermodynamically stable, layered, MAB phases promising for synthesis, we herein explore the phase stability of ternary MAB phases by considering both orthorhombic and hexagonal crystal symmetries for various compositions (MAB, M2AB2, M3AB4, M4AB4, and M4AB6 where M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, and Co, A = Al, Ga, and In, and B is boron). The thermodynamic stability of seven previously synthesized MAB phases is confirmed, three additional phases are predicted to be stable, and 23 phases are found to be close to stable. Furthermore, the crystal symmetry preference for forming orthorhombic or hexagonal crystal structures is investigated where the considered Al-based MAB phases tend to favour orthorhombic structures whereas Ga- and In-based phases in general prefer hexagonal structures. The theoretically predicted stable MAB phases along with the structural preference is intended to both guide experimental efforts and to give an insight into the stability for different crystal symmetries of MAB phases.

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  • 43.
    Casellas, Nicolas M.
    et al.
    UAM, Spain; IMDEA Nanociencia, Spain.
    Urbanaviciute, Indre
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Cornelissen, Tim
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Berrocal, Jose Augusto
    Eindhoven Univ Technol, Netherlands.
    Torres, Tomas
    IMDEA Nanociencia, Spain; UAM, Spain.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Garcia-Iglesias, Miguel
    UAM, Spain; IMDEA Nanociencia, Spain.
    Resistive switching in an organic supramolecular semiconducting ferroelectric2019In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, no 60, p. 8828-8831Article in journal (Refereed)
    Abstract [en]

    The combination of switchable dipolar side groups and the semiconducting core of the newly synthetized C-3-symmetric benzotrithiophene molecule (BTTTA) leads to an ordered columnar material showing continuous tunability from injection- to bulk-limited conductivity modulation.

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  • 44.
    Cemin, Felipe
    et al.
    Univ Paris Saclay, France.
    Tsukamoto, Makoto
    Tokyo Metropolitan Univ, Japan.
    Keraudy, Julien
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Antunes, Vinicius Gabriel
    Univ Estadual Campinas, Brazil.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Alvarez, Fernando
    Univ Estadual Campinas, Brazil.
    Minea, Tiberiu
    Univ Paris Saclay, France.
    Lundin, Daniel
    Univ Paris Saclay, France.
    Low-energy ion irradiation in HiPIMS to enable anataseTiO(2) selective growth2018In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 51, no 23, article id 2353011Article in journal (Refereed)
    Abstract [en]

    High power impulse magnetron sputtering (HiPIMS) has already demonstrated great potential for synthesizing the high-energy crystalline phase of titanium dioxide (rutile Ti-O2) due to large quantities of highly energetic ions present in the discharge. In this work, it is shown that the metastable anatase phase can also be obtained by HiPIMS. The required deposition conditions have been identified by systematically studying the phase formation, microstructure and chemical composition as a function of mode of target operation as well as of substrate temperature, working pressure, and peak current density. It is found that films deposited in the metal and transition modes are predominantly amorphous and contain substoichiometric TiOx compounds, while in compound mode they are well-crystallized and present only O2- ions bound to Ti4+, i.e. pure TiO2. Anatase TiO2 films are obtained for working pressures between 1 and 2 Pa, a peak current density of similar to 1 A cm(-2) and deposition temperatures lower than 300 degrees C. Rutile is favored at lower pressures (amp;lt; 1 Pa) and higher peak current densities (amp;gt;2 A cm(-2)), while amorphous films are obtained at higher pressures (greater than or similar to 5 Pa). Microstructural characterization of selected films is also presented.

  • 45.
    Champagne, A.
    et al.
    UCLouvain, Belgium.
    Chaix-Pluchery, O.
    Univ Grenoble Alpes, France.
    Ouisse, T.
    Univ Grenoble Alpes, France.
    Pinek, D.
    Univ Grenoble Alpes, France.
    Gelard, I
    Univ Grenoble Alpes, France.
    Jouffret, L.
    Univ Clermont Auvergne, France.
    Barbier, M.
    Univ Grenoble Alpes, France; European Synchrotron Radiat Facil, France.
    Wilhelm, F.
    European Synchrotron Radiat Facil, France.
    Tao, Quanzheng
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barsoum, M. W.
    Drexel Univ, PA 19104 USA.
    Charlier, J-C
    UCLouvain, Belgium.
    First-order Raman scattering of rare-earth containing i-MAX single crystals (Mo2/3RE1/3)(2)AlC (RE = Nd, Gd, Dy, Ho, Er)2019In: Physical Review Materials, E-ISSN 2475-9953, Vol. 3, no 5, article id 053609Article in journal (Refereed)
    Abstract [en]

    Herein, we report on the growth of single crystals of various (Mo2/3RE1/3)(2)AlC (RE = Nd, Gd, Dy, Ho, Er) i-MAX phases and their Raman characterization. Using first principles, the wave numbers of the various phonon modes and their relative atomic displacements are calculated and compared to experimental results. Twelve high-intensity Raman peaks are identified as the fingerprint of this new family of rare-earth containing i-MAX phases, thus being a useful tool to investigate their corresponding composition and structural properties. Indeed, while a redshift is observed in the low-wave-number range due to an increase of the rare-earth atomic mass when moving from left to right on the lanthanide row, a blueshift is observed for most of the high-wave-number modes due to a strengthening of the bonds. A complete classification of bond stiffnesses is achieved based on the direct dependence of a phonon mode wave number with respect to the bond stiffness. Finally, STEM images are used to confirm the crystal structure.

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  • 46.
    Chang, Jui-Che
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Controlled growth of metastable Ta3N5 semiconducting films2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The semiconductor tritantalum pentanitride (Ta3N5) is a promising material for green energy applications, specifically in the photoelectrolysis of water to produce oxygen and hydrogen. With a bandgap of approximately 2 eV, Ta3N5 is well-suited for efficient solar light absorption across a broad spectrum, and its band positions align favorably with the redox potential of water. Theoretically, this material could achieve a solar-to-hydrogen efficiency of up to 15.9%. However, the intricate nature of the Ta-N compounds and its metastability have limited research into the development of high-quality Ta3N5.   

    In this thesis, the metastable Ta3N5 films were grown using two types of reactive magnetron sputtering techniques, direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS). Several key parameters were found to stabilize the formation of Ta3N5 phase, including the amount of oxygen in a gas mixture of Ar and N2, total working pressure, the Ta2O5 seed layer, and Ar/N2 partial pressure ratio.   

    First, sputter growth of Ta-N film using a gas mixture of Ar and N2 without oxygen gas, only metallic -TaN and ε-TaN phase were formed. After introducing a small amount of oxygen in the process gas (~2% of total working pressure), the oxygen atoms, with higher electronegativity, replace nitrogen atoms to trigger and stabilize the formation of crystalline Ta3N5-type structure. In addition, with a suitable Ar/N2 partial pressure ratio for Ta3N5 formation, a low-degree fiber-textural orthorhombic Ta3N5 film was formed at the total working pressure range from 5 to 30 mTorr. At 40 mTorr total working pressure, the deposited film transforms to O-rich amorphous Ta-O-N compound. Second, the effect of Ta2O5 seed layer on the control of Ta-N phase was studied. The Ta3N5 phase can be grown only with a Ta2O5 seed layer assistance. Without the seed layer, only metallic TaN phases were formed no matter if the film was grown with or without oxygen assistance. Furthermore, domain epitaxial growth of Ta3N5 film on sapphire substrate was achieved through the control of seed layer’s thickness and crystallinity. While the film was grown on an amorphous TaOx seed layer, the Ta3N5 structure becomes polycrystalline. Third, the formation mechanism and epitaxial growth were studied through microstructural analysis in combination of first-principle density-functional theory calculations. Time-dependent growth evolution of Ta3N5 films combined with HRTEM and EDX measurement revealed that the nitridation of Ta2O5 seed layer and Ta-N film deposition occurs simultaneously at the beginning of the Ta3N5 deposition. Further deposition, the Ta3N5 layer was dominated by {00k} domain mixed with (113) domain with a thin TaN layer between Ta3N5 layer and substrate. Last, various Ta-N compounds were grown via controlling the Ar/N2 partial pressure ratio and total working pressure. When the reactive gas was changed from pure Ar to pure nitrogen, the deposited films transformed from Ta metal (mixed with TaOx), TaN, TaN mixed with Ta3N5 to polycrystalline Ta3N5 phase. 

    To summarize the work conducted in this thesis, I have established a reproducible and precise method for cultivating metastable Ta3N5 through the magnetron sputter deposition technique. The elucidated growth mechanism holds promise for synthesizing Ta3N5 on diverse substrates using alternative techniques, ensuring a controlled and adaptable approach. 

    List of papers
    1. Orthorhombic Ta3-xN5-yOy thin films grown by unbalanced magnetron sputtering: The role of oxygen on structure, composition, and optical properties
    Open this publication in new window or tab >>Orthorhombic Ta3-xN5-yOy thin films grown by unbalanced magnetron sputtering: The role of oxygen on structure, composition, and optical properties
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    2021 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 406, article id 126665Article in journal (Refereed) Published
    Abstract [en]

    Direct growth of orthorhombic Ta3N5-type Ta-O-N compound thin films, specifically Ta3-xN5-yOy, on Si and sapphire substrates with various atomic fractions is realized by unbalanced magnetron sputtering. Low-degree fiber-textural Ta3-xN5-yOy films were grown through reactive sputtering of Ta in a gas mixture of N-2, Ar, and O-2 with keeping a partial pressure ratio of 3:2:0.1 in a total working pressure range of 5-30 mTorr. With increasing total pressure from 5 to 30 mTorr, the atomic fraction of O in the as-grown Ta3-xN5-yOy films was found to increase from 0.02 to 0.15 while that of N and Ta decrease from 0.66 to 0.54 and 0.33 to 0.31, respectively, leading to a decrease in b lattice constant up to around 1.3%. Metallic TaNx phases were formed without oxygen. For a working pressure of 40 mTorr, an amorphous, O-rich Ta-N-O compound film with a high O fraction of similar to 0.48, was formed, mixed with non-stoichiometric TaON and Ta2O5. By analyzing the plasma discharge, the increasing O incorporation is associated with oxide formation on top of the Ta target due to a higher reactivity of Ta with O than with N. The increase of O incorporation in the films also leads to a optical bandgap widening from similar to 2.22 to similar to 2.96 eV, which is in agreement with the compositional and structural changes from a crystalline Ta3-xN5-yOy to an amorphous O-rich Ta-O-N compound.

    Place, publisher, year, edition, pages
    ELSEVIER SCIENCE SA, 2021
    Keywords
    Ta3N5; Magnetron sputtering; XRD; XPS; ERDA; Optical absorption spectroscopy
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:liu:diva-173006 (URN)10.1016/j.surfcoat.2020.126665 (DOI)000604750600025 ()
    Note

    Funding Agencies|Vetenskapseddet [2018-04198]; Energimyndigheten [46658-1]; Stiftelsen 011e Engkvist Byggmastare [197-0210]; Linkoping University Library; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]; VR-RFI [821-2012-5144, 2017-00646_9]; Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research [RIF14-0053, 5E13-0333]

    Available from: 2021-01-27 Created: 2021-01-27 Last updated: 2023-12-21
    2. Domain epitaxial growth of Ta3N5 film on c-plane sapphire substrate
    Open this publication in new window or tab >>Domain epitaxial growth of Ta3N5 film on c-plane sapphire substrate
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    2022 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 443, article id 128581Article in journal (Refereed) Published
    Abstract [en]

    Tritantalum pentanitride (Ta3N5) semiconductor is a promising material for photoelectrolysis of water with high efficiency. Ta3N5 is a metastable phase in the complex system of TaN binary compounds. Growing stabilized single-crystal Ta3N5 films is correspondingly challenging. Here, we demonstrate the growth of a nearly single-crystal Ta3N5 film with epitaxial domains on c-plane sapphire substrate, Al2O3(0001), by magnetron sputter epitaxy. Introduction of a small amount ~2% of O2 into the reactive sputtering gas mixed with N2 and Ar facilitates the formation of a Ta3N5 phase in the film dominated by metallic TaN. In addition, we indicate that a single-phase polycrystalline Ta3N5 film can be obtained with the assistance of a Ta2O5 seed layer. With controlling thickness of the seed layer smaller than 10 nm and annealing at 1000 °C, a crystalline β phase Ta2O5 was formed, which promotes the domain epitaxial growth of Ta3N5 films on Al2O3(0001). The mechanism behind the stabilization of the orthorhombic Ta3N5 structure resides in its stacking with the ultrathin seed layer of orthorhombic β-Ta2O5, which is energetically beneficial and reduces the lattice mismatch with the substrate.

    Place, publisher, year, edition, pages
    Elsevier, 2022
    Keywords
    Ta3N5, Sputtering, MSE, XRD, XPS, Water splitting, Single crystal
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-188556 (URN)10.1016/j.surfcoat.2022.128581 (DOI)000868328000003 ()
    Note

    Funding: Swedish Research Council [2018-04198, 2021-00357]; Swedish Energy Agency [46658-1]; Stiftelsen Olle Engkvist Byggmastare [197-0210]; Linkoping University Library; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]

    Available from: 2022-09-16 Created: 2022-09-16 Last updated: 2023-12-21Bibliographically approved
    3. HiPIMS-grown AlN buffer for threading dislocation reduction in DC-magnetron sputtered GaN epifilm on sapphire substrate
    Open this publication in new window or tab >>HiPIMS-grown AlN buffer for threading dislocation reduction in DC-magnetron sputtered GaN epifilm on sapphire substrate
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    2023 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 217, article id 112553Article in journal (Refereed) Published
    Abstract [en]

    Gallium nitride (GaN) epitaxial films on sapphire (Al2O3) substrates have been grown using reactive magnetron sputter epitaxy with a liquid Ga target. Threading dislocations density (TDD) of sputtered GaN films was reduced by using an inserted high-quality aluminum nitride (AlN) buffer layer grown by reactive high power impulse magnetron sputtering (R-HiPIMS) in a gas mixture of Ar and N2. After optimizing the Ar/N2 pressure ratio and deposition power, a high-quality AlN film exhibiting a narrow full-width at half-maximum (FWHM) value of the double-crystal x-ray rocking curve (DCXRC) of the AlN(0002) peak of 0.086° was obtained by R-HiPIMS. The mechanism giving rise the observed quality improvement is attributed to the enhancement of kinetic energy of the adatoms in the deposition process when operated in a transition mode. With the inserted HiPIMS-AlN as a buffer layer for direct current magnetron sputtering (DCMS) GaN growth, the FWHM values of GaN(0002) and (10 1‾ 1) XRC decrease from 0.321° to 0.087° and from 0.596° to 0.562°, compared to the direct growth of GaN on sapphire, respectively. An order of magnitude reduction from 2.7 × 109 cm−2 to 2.0 × 108 cm−2 of screw-type TDD calculated from the FWHM of the XRC data using the inserted HiPIMS-AlN buffer layer demonstrates the improvement of crystal quality of GaN. The result of TDD reduction using the HiPIMS-AlN buffer was also verified by weak beam dark-field (WBDF) cross-sectional transmission electron microscopy (TEM).

    Place, publisher, year, edition, pages
    PERGAMON-ELSEVIER SCIENCE LTD, 2023
    Keywords
    GaN; Magnetron sputtering; HiPIMS; Dislocations; XRCTEM
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-197990 (URN)10.1016/j.vacuum.2023.112553 (DOI)001072124300001 ()
    Funder
    Swedish Research CouncilSwedish Energy AgencyThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Carl Tryggers foundation Olle Engkvists stiftelse
    Note

    Funding agencies: This research was funded by Vetenskapsrådet (grant number 2018-04198), Energimyndigheten (grant number 46658-1), Carl Tryggers Stiftelse (grant number CTS 22:2029) and Stiftelsen Olle Engkvist Byggmästare (grant number 197-0210). The Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU 2009-00971) is acknowledged for financial support. We acknowledge STINT foundation, Sweden, for supporting this international collaboration (grant number: MG2019-8485).

    Available from: 2023-09-20 Created: 2023-09-20 Last updated: 2023-12-21
  • 47.
    Chang, Jui-Che
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sortica, Mauricio A.
    Uppsala Univ, Sweden.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Bakhit, Babak
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hu, Zhang-Jun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Orthorhombic Ta3-xN5-yOy thin films grown by unbalanced magnetron sputtering: The role of oxygen on structure, composition, and optical properties2021In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 406, article id 126665Article in journal (Refereed)
    Abstract [en]

    Direct growth of orthorhombic Ta3N5-type Ta-O-N compound thin films, specifically Ta3-xN5-yOy, on Si and sapphire substrates with various atomic fractions is realized by unbalanced magnetron sputtering. Low-degree fiber-textural Ta3-xN5-yOy films were grown through reactive sputtering of Ta in a gas mixture of N-2, Ar, and O-2 with keeping a partial pressure ratio of 3:2:0.1 in a total working pressure range of 5-30 mTorr. With increasing total pressure from 5 to 30 mTorr, the atomic fraction of O in the as-grown Ta3-xN5-yOy films was found to increase from 0.02 to 0.15 while that of N and Ta decrease from 0.66 to 0.54 and 0.33 to 0.31, respectively, leading to a decrease in b lattice constant up to around 1.3%. Metallic TaNx phases were formed without oxygen. For a working pressure of 40 mTorr, an amorphous, O-rich Ta-N-O compound film with a high O fraction of similar to 0.48, was formed, mixed with non-stoichiometric TaON and Ta2O5. By analyzing the plasma discharge, the increasing O incorporation is associated with oxide formation on top of the Ta target due to a higher reactivity of Ta with O than with N. The increase of O incorporation in the films also leads to a optical bandgap widening from similar to 2.22 to similar to 2.96 eV, which is in agreement with the compositional and structural changes from a crystalline Ta3-xN5-yOy to an amorphous O-rich Ta-O-N compound.

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  • 48.
    Chen, Liugang
    et al.
    Katholieke Univ Leuven, Belgium.
    Dahlqvist, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lapauw, Thomas
    Katholieke Univ Leuven, Belgium; SCK CEN, Belgium.
    Tunca, Bensu
    Katholieke Univ Leuven, Belgium; SCK CEN, Belgium.
    Wang, Fei
    Katholieke Univ Leuven, Belgium.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Meshkian, Rahele
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lambrinou, Konstantina
    SCK CEN, Belgium.
    Blanpain, Bart
    Katholieke Univ Leuven, Belgium.
    Vleugels, Jozef
    Katholieke Univ Leuven, Belgium.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Theoretical Prediction and Synthesis of (Cr2/3Zr1/3)(2)AIC i-MAX Phase2018In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, no 11, p. 6237-6244Article in journal (Refereed)
    Abstract [en]

    Guided by predictive theory, a new compound with chemical composition (Cr2/3Zr1/3)(2)AlC was synthesized by hot pressing of Cr, ZrH2, Al, and C mixtures at 1300 degrees C. The crystal structure is monoclinic of space group C2/c and displays in-plane chemical order in the metal layers, a so-called i-MAX phase. Quantitative chemical composition analyses confirmed that the primary phase had a (Cr2/3Zr1/3)(2)AlC stoichiometry, with secondary Cr2AlC, AlZrC2, and ZrC phases and a small amount of Al-Cr intermetallics. A theoretical evaluation of the (Cr2/3Zr1/3)(2)AlC magnetic structure was performed, indicating an antiferromagnetic ground state. Also (Cr2/3Zr1/3)(2)AlC, of the same structure, was predicted to be stable.

  • 49.
    Chen, Zhe
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Hörnqvist Colliander, Magnus
    Department of Physics, Chalmers University of Technology, Gothenburg, Sweden.
    Sundell, Gustav
    Department of Physics, Chalmers University of Technology, Gothenburg, Sweden.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Zhou, Jinming
    Division of Production and Materials Engineering, Lund University, Sweden.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Nano-scale characterization of white layer in broached Inconel 7182017In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 684, p. 373-384Article in journal (Refereed)
    Abstract [sv]

    The formation mechanism of white layers during broaching and their mechanical properties are not well investigated and understood to date. In the present study, multiple advanced characterization techniques with nano-scale resolution, including transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT) as well as nano-indentation, have been used to systematically examine the microstructural evolution and corresponding mechanical properties of a surface white layer formed when broaching the nickel-based superalloy Inconel 718.

    TEM observations showed that the broached white layer consists of nano-sized grains, mostly in the range of 20–50 nm. The crystallographic texture detected by TKD further revealed that the refined microstructure is primarily caused by strong shear deformation. Co-located Al-rich and Nb-rich fine clusters have been identified by APT, which are most likely to be γ′ and γ′′ clusters in a form of co-precipitates, where the clusters showed elongated and aligned appearance associated with the severe shearing history. The microstructural characteristics and crystallography of the broached white layer suggest that it was essentially formed by adiabatic shear localization in which the dominant metallurgical process is rotational dynamic recrystallization based on mechanically-driven subgrain rotations. The grain refinement within the white layer led to an increase of the surface nano-hardness by 14% and a reduction in elastic modulus by nearly 10% compared to that of the bulk material. This is primarily due to the greatly increased volume fraction of grain boundaries, when the grain size was reduced down to the nanoscale.

  • 50.
    Chen, Zhiwen
    et al.
    Shanghai Univ, Peoples R China.
    Liu, Xiao
    Shanghai Univ, Peoples R China.
    Xin, Peijun
    Shanghai Univ, Peoples R China.
    Wang, Haitao
    Shanghai Univ, Peoples R China.
    Wu, Ye
    Shanghai Univ, Peoples R China.
    Gao, Chunyan
    Shanghai Univ, Peoples R China.
    He, Qingquan
    Shanghai Univ, Peoples R China.
    Jiang, Yong
    Shanghai Univ, Peoples R China.
    Hu, Zhang-Jun
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering. Shanghai Univ, Peoples R China.
    Huang, Shoushuang
    Shanghai Univ, Peoples R China.
    Interface engineering of NiS@MoS2 core-shell microspheres as an efficient catalyst for hydrogen evolution reaction in both acidic and alkaline medium2021In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 853, article id 157352Article in journal (Refereed)
    Abstract [en]

    Electrochemical splitting of water is one of the most reliable and effective ways for the sustainable production of pure hydrogen on a large scale, while the core of this technology lies in the development of highly active non-noble-metal-based electrocatalysts to lower the large dynamic overpotentials of electrode materials. Here, an interface engineering strategy is demonstrated to construct an efficient and stable catalyst based on NiS@MoS2 core-shell hierarchical microspheres for the hydrogen evolution reactions (HER). The ultrathin MoS2 nanosheets in-situ grow on the surface of NiS hierarchical micro-sized spheres constructed by porous nanoplates, endowing the composites with rich interfaces, well-exposed electroactive edges, high structural porosity and fast transport channels. These advantages are favorable for the improvement of catalytic sites and the transport of catalysis-relevant species. More importantly, the intimate contact between MoS2 nanosheets and NiS nanoplates synergistically favors the chemical sorption of hydrogen intermediates, thereby reducing the reaction barrier and accelerating the HER catalytic process. As a result, the optimized NiS@MoS2 catalyst manifests impressive HER activity and durability, with a low overpotential of 208 mV in 0.5 M H2SO4 and 146 mV in 1.0 M KOH at 10 mA cm(-2), respectively. This work not only provides an effective way to construct core-shell hierarchical microspheres but also a multiscale strategy to regulate the electronic structure of heterostructured materials for energy-related applications. (C) 2020 Elsevier B.V. All rights reserved.

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