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Structural properties of amorphous metal carbides: Theory and experiment
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
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2012 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 60, no 12, 4720-4728 p.Article in journal (Refereed) Published
Abstract [en]

By means of theoretical modeling and experimental synthesis and characterization, we investigate the structural properties of amorphous Zr-Si-C. Two chemical compositions are selected: Zr0.31Si0.29C0.40 and Zr0.60Si0.33C0.07. Amorphous structures are generated in the theoretical part of our work by the stochastic quenching (SQ) method, and detailed comparison is made regarding the structure and density of the experimentally synthesized films. These films are analyzed experimentally using X-ray absorption spectroscopy, transmission electron microscopy and X-ray diffraction. Our results demonstrate a remarkable agreement between theory and experiment concerning bond distances and atomic coordination of this complex amorphous metal carbide. The demonstrated power of the SQ method opens up avenues for theoretical predictions of amorphous materials in general.

Place, publisher, year, edition, pages
2012. Vol. 60, no 12, 4720-4728 p.
Keyword [en]
Amorphous materials, Ab initio calculations, X-ray absorption spectroscopy, Metal carbide glasses, Atomic structure
National Category
Inorganic Chemistry
Research subject
Chemistry with specialization in Inorganic Chemistry
URN: urn:nbn:se:uu:diva-181138DOI: 10.1016/j.actamat.2012.04.044ISI: 000307415200006OAI: oai:DiVA.org:uu-181138DiVA: diva2:553229
Available from: 2012-09-18 Created: 2012-09-17 Last updated: 2015-07-07Bibliographically approved
In thesis
1. Synthesis and Characterization of Amorphous Carbide-based Thin Films
Open this publication in new window or tab >>Synthesis and Characterization of Amorphous Carbide-based Thin Films
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, research on synthesis, structure and characterization of amorphous carbide-based thin films is presented. Crystalline and nanocomposite carbide films can exhibit properties such as high electrical conductivity, high hardness and low friction and wear. These properties are in many cases structure-related, and thus, within this thesis a special focus is put on how the amorphous structure influences the material properties.

Thin films within the Zr-Si-C and Cr-C-based systems have been synthesized by magnetron sputtering from elemental targets. For the Zr-Si-C system, completely amorphous films were obtained for silicon contents of 20 at.% or higher. Modeling of these films, as well as experimental results suggest that the films exhibit a network-type structure where the bond types influence the material properties. Higher hardness and resistivity were observed with high amounts of covalent Si-C bonds.

Several studies were performed in the Cr-C-based systems. Cr-C films deposited in a wide composition range and with substrate temperatures of up to 500 °C were found to be amorphous nanocomposites, consisting of amorphous chromium carbide (a-CrCx) and amorphous carbon (a-C) phases. The carbon content in the carbidic phase was determined to about 30-35 at.% for most films. The properties of the Cr-C films were very dependent of the amount of a-C phase, and both hardness and electrical resistivity decreased with increasing a-C contents. However, electrochemical analysis showed that Cr-C films deposited at higher substrate temperature and with high carbon content exhibited very high oxidation resistance. In addition, nanocomposite films containing Ag nanoparticles within an amorphous Cr-C matrix were studied in an attempt to improve the tribological properties. No such improvements were observed but the films exhibited a better contact resistance than the corresponding binary Cr-C films. Furthermore, electrochemical analyses showed that Ag nanoparticles on the surface affected the formation of a stable passive film, which would make the Cr-C/Ag films less resilient to oxidation than the pure Cr-C films.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 63 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1239
Amorphous, coating, thin film, nanocomposite, sputter deposition, PVD, XPS, SEM, TEM, electrical properties, mechanical properties
National Category
Inorganic Chemistry
urn:nbn:se:uu:diva-247282 (URN)978-91-554-9198-7 (ISBN)
Public defence
2015-05-08, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Available from: 2015-04-16 Created: 2015-03-16 Last updated: 2015-07-07

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Kadas, KrisztinaAndersson, MatildaKaris, OlofButorin, Sergei M.Jansson, UlfEriksson, Olle
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