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Jansson, U. & Lewin, E. (2019). Carbon-containing multi-component thin films. Thin Solid Films, 688, Article ID 137411.
Open this publication in new window or tab >>Carbon-containing multi-component thin films
2019 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 688, article id 137411Article, review/survey (Refereed) Published
Abstract [en]

High entropy alloys (HEAs) have been a hot research area for many years. They are solid solutions of at least five elements in approximately equimolar compositions. The HEAs are assumed to be stabilized by a high entropy of mixing favouring a solid solution phase instead of a mixture of intermetallic phases. The importance of entropy of mixing and the true nature of HEAs are debated but the concept has contributed to an interesting development of new alloys. They idea of stabilizing solid solutions with many elements have recently been expanded to nitrides, borides, oxides and carbides. Furthermore, a growing number of thin film studies of these compounds are now published. In this paper we summarise recent results from studies of carbon-containing multi-component thin films based on the HEA concept. We will summarise some general observations connected to "high-entropy" materials. We also describe some general trends in metal-carbon interactions for transition metals and discuss how they should influence the formation of multi-component carbides. A summary of results on bulk multi-component carbide materials is also presented. We review published studies of carbon-containing multi-component thin films mainly deposited with magnetron-sputtering. The crystal structure, microstructure and properties of these films are described. Finally, we highlight some interesting topics for future research.

Keywords
Review, High entropy materials, Multi-component materials, Carbides, Thin-films
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-395626 (URN)10.1016/j.tsf.2019.137411 (DOI)000485256500007 ()
Funder
Swedish Research Council
Available from: 2019-10-23 Created: 2019-10-23 Last updated: 2019-10-23Bibliographically approved
von Fieant, K., Johansson, F. O. L., Balmes, O., Lindblad, R., Riekehr, L., Lindblad, A. & Lewin, E. (2019). In Situ Formation of Ge Nanoparticles by Annealing of Al-Ge‑N ThinFilms Followed by HAXPES and XRD. Inorganic Chemistry, 58(16), 11100-11109
Open this publication in new window or tab >>In Situ Formation of Ge Nanoparticles by Annealing of Al-Ge‑N ThinFilms Followed by HAXPES and XRD
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2019 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, no 16, p. 11100-11109Article in journal (Refereed) Published
Abstract [en]

Ge nanoparticles embedded in thin films have attracted a lot of attention due to their promising optical and electronic properties that can be tuned by varying the particle size and choice of matrix material. In this study, Ge nanoparticle formation was investigated for Al-Ge-N based thin films by simultaneous measurements of HAXPES and grazing incidence XRD during in situ annealing in vacuum conditions. As-deposited Al-Ge-N thin films, synthesized by reactive dc magnetron sputtering, consisted of a nanocrystalline (Al1–xGex)Ny solid solution and an amorphous tissue phase of Ge3Ny. Upon annealing to 750 °C, elemental Ge was formed shown by both HAXPES and XRD measurements, and N2 gas was released as measured by a mass spectrometer. Postannealed ex situ analysis by SEM and TEM showed that the elemental Ge phase formed spherical nanoparticles on the surface of the film, with an average size of 210 nm. As the annealing temperature increased further to 850 °C, the Ge particles on the film surface evaporated, while the phase segregation of Ge still could be observed within the film. Thus, these results show the possibility for a controlled synthesis of Ge nanoparticles through annealing of Al-Ge-N thin films to produce materials suitable for use in electronic or optoelectronic devices.

National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-392698 (URN)10.1021/acs.inorgchem.9b01631 (DOI)000482173300075 ()31381309 (PubMedID)
Funder
Swedish Research Council, 2014-6463EU, FP7, Seventh Framework Programme, INCA 600398
Available from: 2019-09-08 Created: 2019-09-08 Last updated: 2019-10-08Bibliographically approved
Fritze, S., Koller, C. M., von Fieandt, L., Malinovskis, P., Johansson, K., Lewin, E., . . . Jansson, U. (2019). Influence of Deposition Temperature on the Phase Evolution of HfNbTiVZr High-Entropy Thin Films. Materials, 12(4), Article ID 587.
Open this publication in new window or tab >>Influence of Deposition Temperature on the Phase Evolution of HfNbTiVZr High-Entropy Thin Films
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2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 4, article id 587Article in journal (Refereed) Published
Abstract [en]

In this study, we show that the phase formation of HfNbTiVZr high-entropy thin films is strongly influenced by the substrate temperature. Films deposited at room temperature exhibit an amorphous microstructure and are 6.5 GPa hard. With increasing substrate temperature (room temperature to 275 degrees C), a transition from an amorphous to a single-phased body-centred cubic (bcc) solid solution occurs, resulting in a hardness increase to 7.9 GPa. A higher deposition temperature (450 degrees C) leads to the formation of C14 or C15 Laves phase precipitates in the bcc matrix and a further enhancement of mechanical properties with a peak hardness value of 9.2 GPa. These results also show that thin films follow different phase formation pathways compared to HfNbTiVZr bulk alloys.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
high-entropy alloys, physical vapour deposition (PVD), metallic glass
National Category
Metallurgy and Metallic Materials Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-380494 (URN)10.3390/ma12040587 (DOI)000460793300037 ()30781407 (PubMedID)
Funder
Swedish Research Council, 2018-04834
Available from: 2019-03-28 Created: 2019-03-28 Last updated: 2019-03-28Bibliographically approved
Cedervall, J., Ivanov, S. A., Lewin, E., Beran, P., Andersson, M. S., Faske, T., . . . Mathieu, R. (2019). On the structural and magnetic properties of the double perovskite Nd2NiMnO6. Journal of materials science. Materials in electronics, 30(17), 16571-16578
Open this publication in new window or tab >>On the structural and magnetic properties of the double perovskite Nd2NiMnO6
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2019 (English)In: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 30, no 17, p. 16571-16578Article in journal (Refereed) Published
Abstract [en]

The structural, electronic and magnetic properties of phase pure and stoichiometric samples of the double perovskite Nd2NiMnO6. Photoectron spectroscopy revels a mixed valence of the transition metal sites where Ni has 3+/2+ oxidation states and Mn has 3+/4+. The compound orders ferromagnetically at 195 K. The magnetic structure was determined from the refinement of the neutron diffraction data. The results suggests that the B-site magnetic moments align along the crystallographic a-direction.

Place, publisher, year, edition, pages
SPRINGER, 2019
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-395325 (URN)10.1007/s10854-019-02035-z (DOI)000486022200078 ()
Funder
Swedish Research Council
Available from: 2019-10-17 Created: 2019-10-17 Last updated: 2019-10-17Bibliographically approved
Saldan, I., Lewin, E., Dobrovetska, O., Karlsson, D., Bilan, O. & Kuntyi, O. (2019). Surface analysis of nickel nanomaterials electrodeposited on graphite surface. Micro & Nano Letters, 14(12), 1233-1237
Open this publication in new window or tab >>Surface analysis of nickel nanomaterials electrodeposited on graphite surface
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2019 (English)In: Micro & Nano Letters, ISSN 1750-0443, E-ISSN 1750-0443, Vol. 14, no 12, p. 1233-1237Article in journal (Refereed) Published
Abstract [en]

Pure Nickel (Ni) and Nickel-Palladium (Ni-Pd) alloy were electrodeposited on graphite surface via pulse electrolysis in dimethyl sulfoxide in form of rods and nanoparticles with a diameter of similar to 100-350 and similar to 10-35 nm, respectively. X-ray photoelectron spectroscopy (XPS) spectra of Ni 2p(3/2) region for these nanomaterials suggests on their surface Ni2+ precursor while after Ar+ ion-etching metallic nickel starts to be dominated. Both Pd-0 and Pd2+ for XPS spectra of Pd 3d(5/2) and 3d(3/2) were observed after electrodeposition. Scanning electron microscope-energy dispersive X-ray and XPS analysis confirmed electrodeposition of nickel nanomaterials in non-aqueous electrolyte. Using a lower concentration of Ni2+ precursor, nanoparticles with an average particle size of similar to 10-23 nm were prepared on a graphite surface.

Place, publisher, year, edition, pages
INST ENGINEERING TECHNOLOGY-IET, 2019
Keywords
particle size, nanoparticles, nickel, graphite, nanofabrication, electrodeposition, X-ray photoelectron spectra, electrolysis, etching, X-ray chemical analysis, scanning electron microscopy, palladium alloys, nickel alloys, C, Ni, NiPd, nonaqueous electrolyte, Ar+ ion-etching metallic nickel, surface Ni2+ precursor, dimethyl sulfoxide, pulse electrolysis, nickel-palladium alloy, electron microscope-energy dispersive X-ray analysis, XPS spectra, ion-etching metallic nickel, X-ray photoelectron spectroscopy spectra, graphite surface, nickel nanomaterials, surface analysis
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-402232 (URN)10.1049/mnl.2019.0319 (DOI)000503179400005 ()
Funder
Swedish Institute, 23891/2017
Available from: 2020-01-16 Created: 2020-01-16 Last updated: 2020-01-16Bibliographically approved
Kumar, A., Wetterskog, E., Lewin, E., Tai, C.-W., Akansel, S., Husain, S., . . . Svedlindh, P. (2018). Effect of in situ electric-field-assisted growth on antiphase boundaries in epitaxial Fe3O4 thin films on MgO. Physical Review Materials, 2(5), Article ID 054407.
Open this publication in new window or tab >>Effect of in situ electric-field-assisted growth on antiphase boundaries in epitaxial Fe3O4 thin films on MgO
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2018 (English)In: Physical Review Materials, ISSN 2475-9953, Vol. 2, no 5, article id 054407Article in journal (Refereed) Published
Abstract [en]

Antiphase boundaries (APBs) normally form as a consequence of the initial growth conditions in all spinel ferrite thin films. These boundaries result from the intrinsic nucleation and growth mechanism, and are observed as regions where the periodicity of the crystalline lattice is disrupted. The presence of APBs in epitaxial films of the inverse spinel Fe3O4 alters their electronic and magnetic properties due to strong antiferromagnetic (AF) interactions across these boundaries. We explore the effect of using in-plane in situ electric-field-assisted growth on the formation of APBs in heteroepitaxial Fe3O4(100)/MgO(100) thin films. The electric-field-assisted growth is found to reduce the AF interactions across APBs and, as a consequence, APB-free thin-film-like properties are obtained, which have been probed by electronic, magnetic, and structural characterization. The electric field plays a critical role in controlling the density of APBs during the nucleation process by providing an electrostatic force acting on adatoms and therefore changing their kinetics. This innovative technique can be employed to grow epitaxial spinel thin films with controlled AF interactions across APBs.

Place, publisher, year, edition, pages
American Physical Society, 2018
Keywords
Fe3O4, Epitaxy, Half-metals, Anti-Phase Boundary, Verwey Transition
National Category
Condensed Matter Physics Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-351161 (URN)10.1103/PhysRevMaterials.2.054407 (DOI)000433037500003 ()
Funder
Knut and Alice Wallenberg Foundation, KAW 2012.0031
Available from: 2018-05-21 Created: 2018-05-21 Last updated: 2018-08-15Bibliographically approved
Fritze, S., Malinovskis, P., Riekehr, L., von Fieandt, L., Lewin, E. & Jansson, U. (2018). Hard and crack resistant carbon supersaturated refractory nanostructured multicomponent coatings. Scientific Reports, 8, Article ID 14508.
Open this publication in new window or tab >>Hard and crack resistant carbon supersaturated refractory nanostructured multicomponent coatings
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2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 14508Article in journal (Refereed) Published
Abstract [en]

The combination of ceramic hardness with high crack resistance is a major challenge in the design of protective thin films. High entropy alloys have shown in earlier studies promising mechanical properties with a potential use as thin film materials. In this study, we show that small amounts of carbon in magnetron-sputtered multicomponent CrNbTaTiW films can lead to a significant increase in hardness. The film properties were strongly dependent on the metal composition and the most promising results were observed for TaW-rich films. They crystallised in a bcc structure with a strong (110) texture and coherent grain boundaries. It was possible to deposit films with 8 at.% C in a supersaturated solid-solution into the bcc structure without carbide formation. A major effect of carbon was a significant grain refinement, reducing the column diameter from approximately 35 to 10 nm. This resulted in an increase in hardness from 14.7 to 19.1 GPa while the reduced E-modulus stayed constant at 322 GPa. The carbon-containing films exhibited extremely little plastic deformation around the indent and no cracks were observed. These results show that supersaturation of carbon into high entropy films can be a promising concept to combine superior hardness with high crack resistance.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2018
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-368107 (URN)10.1038/s41598-018-32932-y (DOI)000445894500011 ()30266967 (PubMedID)
Funder
Swedish Research Council, 621-2012-4359Swedish Research Council, 622-2008-405Swedish Foundation for Strategic Research , RMA11-0029
Available from: 2018-12-05 Created: 2018-12-05 Last updated: 2018-12-05Bibliographically approved
Johansson, K. & Lewin, E. (2018). Influence of oxygen content on structure and material properties of reactively sputtered Al-Ge-O-N thin films. Journal of Alloys and Compounds, 738, 515-527
Open this publication in new window or tab >>Influence of oxygen content on structure and material properties of reactively sputtered Al-Ge-O-N thin films
2018 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 738, p. 515-527Article in journal (Refereed) Published
Abstract [en]

Ternary Al-Ge-N and quaternary Al-Ge-O-N coatings were deposited by reactive dc magnetron cosputtering of Al and Ge targets in an Ar/N-2 or Ar/N-2/O-2 atmosphere at a substrate temperature of 250 degrees C. The structure and material properties of the coatings were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), nanoindentation, UV-vis spectroscopy and optical profilometry. In agreement with literature, the ternary Al-Ge-N coatings were found to be nanocomposite materials with nanocrystalline (Al1-xGex) N-y solid solution phase in a Ge3N4-z amorphous matrix. The Al-Ge-O-N coatings consisted of a nanocrystalline wurzite-type (Al1-xGex)( N1-yOy) solid solution phase for low oxygen concentrations with a possible co-existence of an amorphous Ge-N matrix phase. For higher O contents, the coatings became X-ray amorphous. The mechanical properties of the Al-Ge-O-N films were improved for low oxygen content, as compared to the ternary Al-Ge-N samples, showing an increase in hardness up to 29 GPa and Young's modulus to 320 GPa. The oxygen addition also resulted in an additional design parameter of the optical properties compared to the ternary Al-Ge-N films. The optical absorption edge was thus tuneable towards both shorter and longer wavelength by changing the O and Ge content respectively, and ranged from 302 to 373 nm, corresponding to an optical bandgap (E-04) between 4.1 and 3.3 eV. After annealing of the Al-Ge-O-N coatings in ultra-high vacuum at 500 degrees C, indications of increased thermal stability for the coating with high oxygen content were observed. For the annealed Al-Ge-O-N films the mechanical properties were improved upon heat treatment, while the optical properties were only slightly changed. These results suggests that coatings of the Al-Ge-O-N system could be suitable as protective optical coatings at elevated temperatures.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2018
Keywords
Reactive sputtering, Al-Ge-O-N, Optical properties, Hard coatings, Thermal stability
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-341556 (URN)10.1016/j.jallcom.2017.12.185 (DOI)000419214800062 ()
Funder
Swedish Research Council, C0514401Swedish Foundation for Strategic Research , RIF14-0053
Available from: 2018-02-13 Created: 2018-02-13 Last updated: 2019-09-08Bibliographically approved
Johansson, K., Riekehr, L., Fritze, S. & Lewin, E. (2018). Multicomponent Hf-Nb-Ti-V-Zr nitride coatings by reactive magnetron sputter deposition. Surface & Coatings Technology, 349, 529-539
Open this publication in new window or tab >>Multicomponent Hf-Nb-Ti-V-Zr nitride coatings by reactive magnetron sputter deposition
2018 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 349, p. 529-539Article in journal (Refereed) Published
Abstract [en]

Multicomponent nitride coatings of the Hf-Nb-Ti-V-Zr system with different Hf content (0-18 at.%) were deposited using reactive dc magnetron sputtering. Coatings with lower Hf content (0-7 at.%) were found to consist of a single solid solution phase with NaCl-type structure (space group Fm-3m). Coatings with higher Hf content (10-18 at.%) showed a two-phase material consisting of cubic Fm-3m and tetragonal I4/m:run solid solution phase. The lattice distortion, estimated by calculating the delta-parameter under the assumption of a single solid solution phase, varied between 3.8 and 4.0% and slightly decreased with increasing Hf content. SEM and TEM cross section images showed a columnar microstructure with columns that were frayed on the surface or throughout the whole column. The column size decreased as Hf content increased. The hardness increased from 8 to 19 GPa with increased Hf content, which most probably is related to the change in microstructure rather than change in lattice distortion. The electrical resistivity for all samples ranged between 231 and 286 mu Omega cm.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2018
Keywords
Multiprincipal element nitride, High-entropy nitride, Two-phase nitride, Transition metal nitride, Tetragonal distortion, Thin films
National Category
Materials Chemistry Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:uu:diva-362098 (URN)10.1016/j.surfcoat.2018.06.030 (DOI)000441492600056 ()
Funder
Swedish Research Council, C0514401Swedish Foundation for Strategic Research , RIF14-0053
Available from: 2018-10-01 Created: 2018-10-01 Last updated: 2019-09-08Bibliographically approved
Johansson, K., Riekehr, L. & Fritze, S. (2018). Multicomponent Hf-Nb-Ti-V-Zr nitride coatings by reactive magnetronsputter deposition. Surface & Coatings Technology, 49(15 sept), 529-539
Open this publication in new window or tab >>Multicomponent Hf-Nb-Ti-V-Zr nitride coatings by reactive magnetronsputter deposition
2018 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 49, no 15 sept, p. 529-539Article in journal (Refereed) Published
Abstract [en]

Multicomponent nitride coatings of the Hf-Nb-Ti-V-Zr system with different Hf content (0–18 at.%) were deposited using reactive dc magnetron sputtering. Coatings with lower Hf content (0–7 at.%) were found to consist of a single solid solution phase with NaCl-type structure (space group Fm-3" role="presentation">m). Coatings with higher Hf content (10–18 at.%) showed a two-phase material consisting of cubic Fm-3" role="presentation">m and tetragonal I4/mmm solid solution phase. The lattice distortion, estimated by calculating the δ-parameter under the assumption of a single solid solution phase, varied between 3.8 and 4.0% and slightly decreased with increasing Hf content. SEM and TEM cross section images showed a columnar microstructure with columns that were frayed on the surface or throughout the whole column. The column size decreased as Hf content increased. The hardness increased from 8 to 19 GPa with increased Hf content, which most probably is related to the change in microstructure rather than change in lattice distortion. The electrical resistivity for all samples ranged between 231 and 286 μΩcm.

National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-392699 (URN)10.1016/j.surfcoat.2018.06.030 (DOI)
Available from: 2019-09-08 Created: 2019-09-08 Last updated: 2019-10-09Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-8617-4834

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