Atomic models of non-stoichiometric layered diborides M$_{1-x}$B$_2$ (M = Mg, Al, Zr and Nb) from first principles

I. R. Shein; A. L. Ivanovskii

doi:10.1016/j.physc.2008.06.009

paper

Atomic models of non-stoichiometric layered diborides M $_{1 - x}$ B $_{2}$ (M = Mg, Al, Zr and Nb) from first principles

arXiv:0804.0894 · doi:10.1016/j.physc.2008.06.009

Abstract

Two atomic models of non-stoichiometric metal diborides M $_{1 - x}$ B $_{2}$ are now assumed: (i) the presence of cation vacancies and (ii) the presence of 'super-stoichiometric' boron which is placed in cation vacancy site. We have performed first principle total energy calculations using the VASP-PAW method with the generalized gradient approximation (GGA) for the exchange-correlation potential in a perspective to reveal the trends of M $_{1 - x}$ B $_{2}$ possible stable atomic configurations depending on the type of M cations (M = Mg, Al, Zr or Nb) and the type of the defects (metal vacancies versus metal vacancies occupied by 'super-stoichiometric' boron in forms of single atoms, dimers B $_{2}$ or trimers B $_{3}$ ). Besides we have estimated the stability of these non-stoichiometric states (on the example of magnesium-boron system) as depending on the possible synthetic routes, namely via solid state reaction method, as well as in reactions between solid boron and Mg vapor; and between these reagents in gaseous phase. We demonstrate that the non-stoichiometric states such as B $_{2}$ and B $_{3}$ placed in metal sites may be stabilized, while the occupation of vacancy sites by single boron atoms is the most unfavorable.

arXiv comment6 pages, 3 fogures

References in corpus (8)

Cited by in corpus (1)

Metal deficient AlB $_{2}$ -type (Ti $_{0.2}$ Zr $_{0.2}$ Hf $_{0.2}$ Nb $_{0.2}$ Ta $_{0.2}$ ) $_{1 - δ}$ B $_{2}$ high-entropy diborides with high hardness

Atomic models of non-stoichiometric layered diborides M1−x​B2​ (M = Mg, Al, Zr and Nb) from first principles

Abstract

References in corpus (8)

Cited by in corpus (1)

Atomic models of non-stoichiometric layered diborides M $_{1 - x}$ B $_{2}$ (M = Mg, Al, Zr and Nb) from first principles