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Högberg, Hans
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Publications (10 of 86) Show all publications
Magnuson, M., Tengdelius, L., Greczynski, G., Eriksson, F., Jensen, J., Lu, J., . . . Högberg, H. (2019). Compositional dependence of epitaxial Tin+1SiCn MAX-phase thin films grown from a Ti3SiC2 compound target. Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, 37(2), Article ID 021506.
Open this publication in new window or tab >>Compositional dependence of epitaxial Tin+1SiCn MAX-phase thin films grown from a Ti3SiC2 compound target
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2019 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, no 2, article id 021506Article in journal (Refereed) Published
Abstract [en]

The authors investigate sputtering of a Ti3SiC2 compound target at temperatures ranging from RT (no applied external heating) to 970 °C as well as the influence of the sputtering power at 850 °C for the deposition of Ti3SiC2 films on Al2O3(0001) substrates. Elemental composition obtained from time-of-flight energy elastic recoil detection analysis shows an excess of carbon in all films, which is explained by differences in the angular distribution between C, Si, and Ti, where C scatters the least during sputtering. The oxygen content is 2.6 at. % in the film deposited at RT and decreases with increasing deposition temperature, showing that higher temperatures favor high purity films. Chemical bonding analysis by x-ray photoelectron spectroscopy shows C–Ti and Si–C bonding in the Ti3SiC2 films and Si–Si bonding in the Ti3SiC2 compound target. X-ray diffraction reveals that the phases Ti3SiC2, Ti4SiC3, and Ti7Si2C5 can be deposited from a Ti3SiC2 compound target at substrate temperatures above 850 °C and with the growth of TiC and the Nowotny phase Ti5Si3Cx at lower temperatures. High-resolution scanning transmission electron microscopy shows epitaxial growth of Ti3SiC2, Ti4SiC3, and Ti7Si2C5 on TiC at 970 °C. Four-point probe resistivity measurements give values in the range ∼120 to ∼450 μΩ cm and with the lowest values obtained for films containing Ti3SiC2, Ti4SiC3, and Ti7Si2C5.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-154004 (URN)10.1116/1.5065468 (DOI)000460437200051 ()
Note

Funding agencies: Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Swedish Energy Research [43606-1]; Carl Tryggers Foundation [CTS16:303, CTS14:310, CTS 17:166]; Knut 

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-03-20Bibliographically approved
Magnuson, M., Greczynski, G., Eriksson, F., Hultman, L. & Högberg, H. (2019). Electronic Structure of ß-Ta Films from X-ray Photoelectron Spectroscopy and First-principles Calculations. Applied Surface Science, 470, 607-612
Open this publication in new window or tab >>Electronic Structure of ß-Ta Films from X-ray Photoelectron Spectroscopy and First-principles Calculations
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2019 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 470, p. 607-612Article in journal (Refereed) Published
Abstract [en]

The electronic structure and chemical bonding of ß-Ta synthesized as a thin 001-oriented film (space group P 21m) is investigated by 4f core level and valence band X-ray photoelectron spectroscopy and compared to α-Ta bulk. For the b-phase, the 4f7/2 peak is located at 21.91 eV and with the 4f5/2 at 23.81 eV which is 0.16 eV higher compared to the corresponding 4f peaks of the a-Ta reference. We suggest that this chemical shift originates from higher resistivity and tensile strain in the ß-Ta film. Furthermore, the 5d-5s states at the bottom of the valence band are shifted by 0.75 eV towards higher binding energy in ß-Ta compared to α-Ta. This is a consequence of the lower number of nearest neighbors with four in ß-Ta compared to eight in the α-Ta phase. The difference in the electronic structures, spectral line shapes of the valence band and the energy positions of the Ta 4f, 5p core-levels of b-Ta versus a-Ta are discussed in relation to calculated states of ß-Ta and α-Ta. In particular, the lower number of states at the Fermi level of ß-Ta (0.557 states/eV/atom) versus α-Ta (1.032 states/eV/atom) that according to Mott’s law should decrease the conductivity in metals and affect the stability by charge redistribution in the valence band. This is experimentally supported from resistivity measurements of the film yielding a value of ~170 µW cm in comparison to α-Ta bulk with a reported value of ~13.1 µW cm.

Keywords
β-Ta films, Valence band measurements, First-principles calculations, X-ray photoelectron spectroscopy, High power impulse magnetron sputtering
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-152876 (URN)10.1016/j.apsusc.2018.11.096 (DOI)000454997100069 ()
Note

Funding agencies: Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University [2009-00971]; Swedish Energy Research [43606-1]; Carl Tryggers Foundation [CTS16:303, CTS14:310, CTS 17:166]; Knut and Alice Wallenber

Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2019-01-21
Magnuson, M., Tengdelius, L., Greczynski, G., Hultman, L. & Högberg, H. (2018). ­Chemical Bonding in Epitaxial ZrB2 Studied by X-ray Spectroscopy. Thin Solid Films, 649, 89-96
Open this publication in new window or tab >>­Chemical Bonding in Epitaxial ZrB2 Studied by X-ray Spectroscopy
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2018 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 649, p. 89-96Article in journal (Refereed) Published
Abstract [en]

The chemical bonding in an epitaxial ZrB2 film is investigated by Zr K-edge (1s) X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies and compared to the ZrB2 compound target from which the film was synthesized as well as a bulk α-Zr reference. Quantitative analysis of X-ray Photoelectron Spectroscopy spectra reveals at the surface: ~5% O in the epitaxial ZrB2 film, ~19% O in the ZrB2 compound target and ~22% O in the bulk α-Zr reference after completed sputter cleaning. For the ZrB2 compound target, X-ray diffraction (XRD) shows weak but visible   11, 111, and 220 peaks from monoclinic ZrO2 together with peaks from ZrB2 and where the intensity distribution for the ZrB2 peaks show a randomly oriented target material.  For the bulk α-Zr reference no peaks from any crystalline oxide were visible in the diffractogram recorded from the 0001-oriented metal. The Zr K-edge absorption from the two ZrB2 samples demonstrate more pronounced oscillations for the epitaxial ZrB2 film than in the bulk ZrB2 attributed to the high atomic ordering within the columns of the film. The XANES exhibits no pre-peak due to lack of p-d hybridization in ZrB2, but with a chemical shift towards higher energy of 4 eV in the film and 6 eV for the bulk compared to α-Zr (17.993 keV) from the charge-transfer from Zr to B. The 2 eV larger shift in bulk ZrB2 material suggests higher oxygen content than in the epitaxial film, which is supported by XPS. In EXAFS, the modelled cell-edge in ZrB2 is slightly smaller in the thin film (a=3.165 Å, c=3.520 Å) in comparison to the bulk target material (a=3.175 Å, c=3.540 Å) while in hexagonal closest-packed metal (α-phase, a=3.254 Å, c=5.147 Å). The modelled coordination numbers show that the EXAFS spectra of the epitaxial ZrB2 film is highly anisotropic with strong in-plane contribution, while the bulk target material is more isotropic. The Zr-B distance in the film of 2.539 Å is in agreement with the calculated value from XRD data of 2.542 Å. This is slightly shorter compared to that in the ZrB2 compound target 2.599 Å, supporting the XANES results of a higher atomic order within the columns of the film compared to bulk ZrB2.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Zirconium boride, thin films, bond distances, chemical bonding, X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-144578 (URN)10.1016/j.tsf.2018.01.021 (DOI)000427524100015 ()
Note

Funding agencies: Swedish Energy Research [43606-1]; Swedish Foundation for Strategic Research (SSF) through the synergy grant FUNCASE [RMA11-0029]; Carl Trygger Foundation [CTS16:303, CTS14:310]; Swedish Research Council (VR) [621-2010 3921]; Knut and Alice Wallenberg Fou

Available from: 2018-01-29 Created: 2018-01-29 Last updated: 2018-11-29Bibliographically approved
Hänninen, T., Schmidt, S., Ivanov, I. G., Jensen, J., Hultman, L. & Högberg, H. (2018). Silicon carbonitride thin films deposited by reactive high power impulse magnetron sputtering. Surface & Coatings Technology, 335, 248-256
Open this publication in new window or tab >>Silicon carbonitride thin films deposited by reactive high power impulse magnetron sputtering
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2018 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 335, p. 248-256Article in journal (Refereed) Published
Abstract [en]

Amorphous silicon carbonitride thin films for biomedical applications were deposited in an industrial coating unit from a silicon target in different argon/nitrogen/acetylene mixtures by reactive high power impulse magnetron sputtering (rHiPIMS). The effects of acetylene (C2H2) flow rate, substrate temperature, substrate bias voltage, and HiPIMS pulse frequency on the film properties were investigated. Low C2H2 flow rates (<10 sccm) resulted in silicon nitride-like film properties, seen from a dense morphology when viewed in cross-sectional scanning electron microscopy, a hardness up to ∼22 GPa as measured by nanoindentation, and Si-N bonds dominating over Si-C bonds in X-ray photoelectron spectroscopy core-level spectra. Higher C2H2 flows resulted in increasingly amorphous carbon-like film properties, with a granular appearance of the film morphology, mass densities below 2 g/cm3 as measured by X-ray reflectivity, and a hardness down to 4.5 GPa. Increasing substrate temperatures and bias voltages resulted in slightly higher film hardnesses and higher compressive residual stresses. The film H/E ratio showed a maximum at film carbon contents ranging between 15 and 30 at.% and at elevated substrate temperatures from 340 °C to 520 °C.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Magnetron sputtering, Silicon carbonitride, Acetylene, Hardness, H/E
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-145178 (URN)10.1016/j.surfcoat.2017.12.037 (DOI)000424720800028 ()
Funder
EU, FP7, Seventh Framework Programme, GA-310477Carl Tryggers foundation , 15:219; 14:431
Available from: 2018-02-13 Created: 2018-02-13 Last updated: 2018-04-03
Magnuson, M., Eriksson, F., Hultman, L. & Högberg, H. (2017). Bonding Structures of ZrHx Thin Films by X-ray Spectroscopy. The Journal of Physical Chemistry C, 121, 25750-25758
Open this publication in new window or tab >>Bonding Structures of ZrHx Thin Films by X-ray Spectroscopy
2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, p. 25750-25758Article in journal (Refereed) Published
Abstract [en]

The variation in local atomic structure and chemical bonding of ZrHx (x=0.15, 0.30, 1.16) magnetron sputtered thin films are investigated by Zr K-edge (1s) X-ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopies. A chemical shift of the Zr K-edge towards higher energy with increasing hydrogen content is observed due to charge-transfer and an ionic or polar covalent bonding component between the Zr 4d and the H 1s states with increasing valency for Zr. We find an increase in the Zr-Zr bond distance with increasing hydrogen content from 3.160 Å in the hexagonal closest-packed metal (a-phase) to 3.395 Å in the understoichiometric d-ZrHx film (CaF2-type structure) with x=1.16 that largely resembles that of bulk d-ZrH2. For yet lower hydrogen contents, the structures are mixed a- and d-phases, while sufficient hydrogen loading (x>1) yields a pure δ-phase that is understoichiometric, but thermodynamically stable. The change in the hydrogen content and strain is discussed in relation to the corresponding change of bond lengths, hybridizations, and trends in electrical resistivity.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-143207 (URN)10.1021/acs.jpcc.7b03223 (DOI)000416496200016 ()
Funder
Swedish Energy Agency, 43606-1Swedish Foundation for Strategic Research , FUNCASE [RMA11-0029]Carl Tryggers foundation , CTS16:303, CTS14:310
Note

Funding agencies: Swedish Government Strategic Research Area in Materials Science on Functiona

Available from: 2017-11-23 Created: 2017-11-23 Last updated: 2018-06-04
Serban, A., Palisaitis, J., Junaid, M., Tengdelius, L., Högberg, H., Hultman, L., . . . Hsiao, C.-L. (2017). Magnetron Sputter Epitaxy of High-Quality GaN Nanorods on Functional and Cost-Effective Templates/Substrates. Energies, 10(9), Article ID 1322.
Open this publication in new window or tab >>Magnetron Sputter Epitaxy of High-Quality GaN Nanorods on Functional and Cost-Effective Templates/Substrates
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2017 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, no 9, article id 1322Article in journal (Refereed) Published
Abstract [en]

We demonstrate the versatility of magnetron sputter epitaxy by achieving high-quality GaN nanorods on different substrate/template combinations, specifically Si, SiC, TiN/Si, ZrB2/Si, ZrB2/SiC, Mo, and Ti. Growth temperature was optimized on Si, TiN/Si, and ZrB2/Si, resulting in increased nanorod aspect ratio with temperature. All nanorods exhibit high purity and quality, proved by the strong bandedge emission recorded with cathodoluminescence spectroscopy at room temperature as well as transmission electron microscopy. These substrates/templates are affordable compared to many conventional substrates, and the direct deposition onto them eliminates cumbersome post-processing steps in device fabrication. Thus, magnetron sputter epitaxy offers an attractive alternative for simple and affordable fabrication in optoelectronic device technology.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI AG, 2017
Keywords
GaN, nanorods, Si, SiC, Ti, Mo, TiN and ZrB2 templates, magnetron sputtering, epitaxy
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-141597 (URN)10.3390/en10091322 (DOI)000411225200078 ()2-s2.0-85029362447 (Scopus ID)
Note

Funding agencies: Swedish Research Council (VR) [621-2012-4420, 621-2013-5360, 2016-04412]; Swedish Governmental Agency for Innovation Systems (VINNOVA) under the VINNMER international qualification program; Swedish Foundation for Strategic Research (SSF) through the Resea

Available from: 2017-10-02 Created: 2017-10-02 Last updated: 2018-05-03Bibliographically approved
Henry, A., Chubarov, M., Czigany, Z., Garbrecht, M. & Högberg, H. (2016). Early stages of growth and crystal structure evolution of boron nitride thin films. Paper presented at 6th International Symposium on Growth of III-Nitrides (ISGN). Japanese Journal of Applied Physics, 55(5), 05FD06
Open this publication in new window or tab >>Early stages of growth and crystal structure evolution of boron nitride thin films
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2016 (English)In: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 55, no 5, p. 05FD06-Article in journal (Refereed) Published
Abstract [en]

A study of the nucleation and crystal structure evolution at the early stages of the growth of sp(2)-BN thin films on 6H-SiC and alpha-Al2O3 substrates is presented. The growth is performed at low pressure and high temperature in a hot wall CVD reactor, using ammonia and triethylboron as precursors, and H-2 as carrier gas. From high-resolution transmission electron microscopy and X-ray thin film diffraction measurements we observe that polytype pure rhombohedral BN (r-BN) is obtained on 6H-SiC substrates. On alpha-Al2O3 an AlN buffer obtained by nitridation is needed to promote the growth of hexagonal BN (h-BN) to a thickness of around 4 nm followed by a transition to r-BN growth. In addition, when r-BN is obtained, triangular features show up in plan-view scanning electron microscopy which are not seen on thin h-BN layers. The formation of BN after already one minute of growth is confirmed by X-ray photoelectron spectroscopy. (C) 2016 The Japan Society of Applied Physics

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2016
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-128949 (URN)10.7567/JJAP.55.05FD06 (DOI)000374697600030 ()
Conference
6th International Symposium on Growth of III-Nitrides (ISGN)
Available from: 2016-06-09 Created: 2016-06-07 Last updated: 2018-03-23
Tengdelius, L., Broitman, E., Lu, J., Eriksson, F., Birch, J., Nyberg, T., . . . Högberg, H. (2016). Hard and elastic epitaxial ZrB2 thin films on Al2O3(0001) substrates deposited by magnetron sputtering from a ZrB2 compound target. Acta Materialia, 111, 166-172
Open this publication in new window or tab >>Hard and elastic epitaxial ZrB2 thin films on Al2O3(0001) substrates deposited by magnetron sputtering from a ZrB2 compound target
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2016 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 111, p. 166-172Article in journal (Refereed) Published
Abstract [en]

Zirconium diboride (ZrB2) exhibits high hardness and high melting point, which is beneficial for applications in for e.g. metal cutting. However, there is limited data on the mechanical properties of ZrB2 films and no data on epitaxial films. In this study, ZrB2(0001) thin films, with thicknesses up to 1.2 μm, have been deposited on Al2O3(0001) substrates by direct current magnetron sputtering from a compound target. X-ray diffraction and transmission electron microscopy show that the films grow epitaxially with two domain types exhibiting different in-plane epitaxial relationships to the substrate. The out-of-plane epitaxial relationship was determined to ZrB2(0001)|Al2O3(0001) and the in-plane relationships of the two domains to ZrB2[100]‖Al2O3[100] and ZrB2[110]‖Al2O3[100]. Mechanical properties of the films, evaluated by nanoindentation, showed that all films exhibit hardness values above 45 GPa, a reduced Young's modulus in the range 350–400 GPa, and a high elastic recovery of 70% at an applied load of 9000 μN.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Borides, Epitaxial growth, Mechanical properties, Nanoindentation, Sputter deposition
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-128612 (URN)10.1016/j.actamat.2016.03.064 (DOI)000375812100018 ()
Note

Funding agencies: Swedish Research Council (VR) [621-2010-3921]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; Knut and Alice Wallenberg Foundation

Available from: 2016-05-25 Created: 2016-05-25 Last updated: 2017-11-30Bibliographically approved
Broitman, E., Tengdelius, L., Hangen, U. D., Lu, J., Hultman, L. & Högberg, H. (2016). High-temperature nanoindentation of epitaxial ZrB2 thin films. Scripta Materialia, 124, 117-120
Open this publication in new window or tab >>High-temperature nanoindentation of epitaxial ZrB2 thin films
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2016 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 124, p. 117-120Article in journal (Refereed) Published
Abstract [en]

We use in-situ heated nanoindentation to investigate the high-temperature nanomechanical properties of epitaxial and textured ZrB2 films deposited by magnetron sputtering. Epitaxial films deposited on 4H-SiC(0001) show a hardness decrease from 47 GPa at room temperature to 33 GPa at 600 °C, while the reduced elastic modulus does not change significantly. High resolution electron microscopy (HRTEM) with selected area electron diffraction of the indented area in a 0001-textured film reveals a retained continuous ZrB2 film and no sign of crystalline phase transformation, despite massive deformation of the Si substrate. HRTEM analysis supports the high elastic recovery of 96% in the films.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Sputtering; Borides; Ceramic thin film; Nanoindentation; Transmission electron microscopy
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-130917 (URN)10.1016/j.scriptamat.2016.06.033 (DOI)000383294200027 ()
Note

Funding agencies: Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Swedish Research Council (VR) [621-2010-3921]

Available from: 2016-08-31 Created: 2016-08-31 Last updated: 2017-11-21Bibliographically approved
Hänninen, T., Schmidt, S., Wissting, J., Jensen, J., Hultman, L. & Högberg, H. (2016). Stoichiometric silicon oxynitride thin films reactively sputtered in Ar/N2O plasmas by HiPIMS. Journal of Physics D: Applied Physics, 49(13), Article ID 135309.
Open this publication in new window or tab >>Stoichiometric silicon oxynitride thin films reactively sputtered in Ar/N2O plasmas by HiPIMS
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2016 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 49, no 13, article id 135309Article in journal (Refereed) Published
Abstract [en]

Silicon oxynitride (SiOxNy, x = 0.2 − 1.3, y = 0.2 − 0.7) thin films were synthesized by reactive high power impulse magnetron sputtering from a pure silicon target in Ar/N2O atmospheres. It is found that the composition of the material can be controlled by the reactive gas flow and the average target power. X-ray photoelectron spectroscopy (XPS) shows that high average powers result in more silicon-rich films, while lower target powers yield silicon-oxide-like material due to more pronounced target poisoning. The amount of nitrogen in the films can be controlled by the percentage of nitrous oxide in the working gas. The nitrogen content remains at a constant level while the target is operated in the transition region between metallic and poisoned target surface conditions. The extent of target poisoning is gauged by the changes in peak target current under the different deposition conditions. XPS also shows that varying concentrations and ratios of oxygen and nitrogen in the films result in film chemical bonding structures ranging from silicon-rich to stoichiometric silicon oxynitrides having no observable Si−Si bond contributions. Spectroscopic ellipsometry shows that the film optical properties depend on the amount and ratio of oxygen and nitrogen in the compound, with film refractive indices measured at 633 nm ranging between those of SiO2 and Si3N4.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2016
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-123382 (URN)10.1088/0022-3727/49/13/135309 (DOI)000371908800023 ()
Note

Funding agencies:  Carl Tryggers Foundation for Scientific Research; European Union under the LifeLongJoints Project [GA-310477]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]

Available from: 2015-12-15 Created: 2015-12-15 Last updated: 2018-02-13Bibliographically approved
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