Pressure dependent elastic and structural ( B3– B1) properties of Ga based monopnictides

Abstract

By formulating an effective interionic interaction potential that incorporates the long-range Coulomb, the covalency effects, the charge transfer caused by the deformation of the electron shells of the overlapping ions, the Hafemeister and Flygare type short-range overlap repulsion extended up to the second neighbour ions and the van der Waals (vdW) interaction, the pressure dependent elastic and thermodynamical properties of the III–V semiconductors as Ga Y ( Y = N, P, As) are studied. The estimated values of phase transition pressure of Ga Y ( Y = N, P, As) are in reasonably good agreement with the available data on the phase transition pressures ( P t = 41, 22, 17 GPa). The vast volume discontinuity in pressure–volume phase diagram identifies a structural phase transition from zinc-blende ( B3) to rock salt ( B1) structure. Later on, the Poisson's ratio ν, the ratio R S/ B of S (Voigt averaged shear modulus) over B (bulk modulus), elastic anisotropy parameter, elastic wave velocity, average wave velocity and Debye temperature as functions of pressure is calculated. From Poisson's ratio and the ratio R S/ B it is inferred that Ga Y ( Y = N, P, As) is brittle [ductile] in zinc-blende ( B3) [Sodium Chloride ( B1)] phase. To our knowledge this is the first quantitative theoretical prediction of the pressure dependence of ductile (brittle) nature of Ga Y compounds and still awaits experimental confirmations.