First‐principles calculations of the mechanical properties of boron‐rich compounds B₁₂N₂X (X = Be, Zn, Cd)

Abstract

Using first‐principles calculations, we have investigated the mechanical properties (bulk, shear, and Young's moduli, Poisson's ratio, and brittleness) of boron‐rich compounds B12N2X (X = Be, Zn, Cd) with the boron carbide‐type structure. The higher shear modulus, 221 GPa for B12N2Be, and the unusual ratio of shear modulus to bulk modulus suggest that the boron‐rich compound B12N2Be is a superhard material. The ionicity of B–X bonds increases with the introduction of metal atoms from Be to Zn to Cd. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

First-principles calculations of boron-rich compounds of B13N2and B12C2X (X = Si, Ge)

“…So far no first-principles calculations on the B 13 N 2 crystal have been reported. Furthermore, among the B 12 -based boron-rich solids, B 12 icosahedra links together by X-X chains or X-Y-X chains (X = C, N, O, P, and As; Y = B, Be, Zn, Cd, et al) [13][14][15][16][17][18][19][20]22]. The larger interstitial distance in the chains can possibly accept other elements to form novel compounds.…”

“…The larger interstitial distance in the chains can possibly accept other elements to form novel compounds. These extraordinary properties render the B 12 -based boronrich solids a class of special materials [22][23][24][25]. In this paper, we performed first-principles calculations for B 13 N 2 ; both non-spin-polarized and spin-polarized calculations are considered.…”

Hardness Prediction and First Principle Study of Re-123(Re = Y, Eu, Pr, Gd) Superconductors

“…The prediction of hardness also helps understanding the other mechanical properties. [2][3][4][5][6][7] The macroscopic physical properties of crystals must have a direct relationship with their constituent chemical bonds. Therefore, for a given crystal, it is reasonable to investigate its origin of hardness by starting from the point of view of the chemical bond.…”

Chemical bond properties and hardness of Ca4REO(BO3)3 (RE=Sm, Gd)

“…Ilyukhin and Dzhurinskii [6] made structural investigations of Ca 4 GdO(BO 3 ) 3 crystallization in the monoclinic biaxial crystal system. However, mechanical properties of Ca 4 REO(BO 3 ) 3 are little investigated, although they are obviously important for all kinds of device application [7][8][9][10][11][12][13]. Therefore, this paper gives a theoretical prediction of hardness values of these crystals by using the chemical bond theory of complex crystals [14][15][16][17] and hardness theory [18][19][20][21].…”