Vacancies and substitutional defects in multicomponent diboride Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 B 2 : first-principle study.

Autor: Matas M; Department of Physics and NTIS-European Centre of Excellence, University of West Bohemia, Univerzitni 8, 30614 Plzen, Czech Republic., Farhadizadeh A; Department of Physics and NTIS-European Centre of Excellence, University of West Bohemia, Univerzitni 8, 30614 Plzen, Czech Republic., Houska J; Department of Physics and NTIS-European Centre of Excellence, University of West Bohemia, Univerzitni 8, 30614 Plzen, Czech Republic.
Jazyk: angličtina
Zdroj: Journal of physics. Condensed matter : an Institute of Physics journal [J Phys Condens Matter] 2021 Dec 13; Vol. 34 (9). Date of Electronic Publication: 2021 Dec 13.
DOI: 10.1088/1361-648X/ac3db4
Abstrakt: We study the hard and electrically conductive multicomponent diboride Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 B 2 with high thermal stability by ab-initio calculations. We focus on the effect of defects (either vacancies or C atoms, both relevant for numerous experiments including our own) on material characteristics. Different types, concentrations and distributions of defects were investigated, and the configurations leading to the lowest formation energies were identified. We show that the replacement of B by C is more unfavorable than the formation of B vacancies. We show that vacancies prefer to coalesce into a larger planar void, minimizing the number of broken B-B bonds and the volume per atom, while carbon substitutions at boron sites do not prefer coalescence and tend to minimize the number of C-C bonds. We show the effect of vacancies on mechanical and electronic properties, and use the results to explain experimental data.
(© 2021 IOP Publishing Ltd.)
Databáze: MEDLINE
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