Structural Stability and Elastic and Electronic Properties of Rhenium Borides: First Principle Investigations

Abstract

The structural stability and elastic and electronic properties of rhenium borides with different boron concentration are calculated systemically by means of first principle total energy calculations. The total energy calculations reveal that the WC-type structure is more energetically favorable for ReB and that the Re(2)P-type structure is more preferred for Re(2)B. The formation enthalpy of these borides have been studied by the solid synthesis routes. The calculated elastic properties indicate that Re(2)B(3), ReB, and Re(2)B phases are also potential hard materials. Although valence-electron density was often employed to evaluate elastic properties of materials, our calculations indicate that the bulk elastic properties of these borides are not direct correlation with their valence-electron density. The analysis of electronic structure, charge density distribution, and Mulliken overlap population provides further understanding of the elastic and superconductivity properties of these borides.

In situ study of the formation of rhenium borides from the elements at high-(p, T) conditions: Extreme incompressibility of Re7B3 and formation of new phases

“…Refs. [27,32]) a phase with lattice parameters close to those observed for the new phases here has been reported. We show that these phases can be recovered.…”

“…The bulk modulus derived from stress-strain calculations agrees with the eos-based value. The values for the c ij obtained here from stress-strain calculations for ReB 2 and Re 7 B 3 agree with those obtained earlier by DFT calculations [27,32,47]. It is worth to mention that the agreement is good although these calculations were performed with other functionals, other pseudopotentials and other DFT-implementations.…”

“…the model structure is elastically unstable. This instability has also been computed by Gou et al [27]. It is worthwhile to note that while for all other borides investigated here the computed lattice parameters agree to better than 1% with the experimental value, with the exception of one lattice parameter of Re 3 B where the difference is still reasonable 2.3%.…”

“…A PBE-GGA value computed by Ref. [27] is slightly lower (378 GPa), which is also expected according to experience [33,15]. In contrast to the results for Re 3 B, for Re 7 B 3 the DFT model is elastically stable.…”

Thermodynamic modeling of the Re–Si–B system

“…Until recently, first-principle (FP) calculations for the enthalpies of formation of Re 3 B, ReB 2 and Re 7 B 3 became available [18]. All these data are listed in Table 2.…”