B1–B2 structural phase transition and elastic properties of UX (X = S, Se, and Te) compounds at high pressure

Abstract

Pressure induced structural phase transformation and mechanical properties of NaCl-type (B1) to CsCl-type (B2) structure in uranium monochalcogenides (UX; X = S, Se, and Te) are presented. An effective interionic interaction potential is constructed, consisting of the long-range Coulomb and the Hafemeister and Flygare type short-range overlap repulsion extended up to the second-neighbour ions and the van der Waals (vdW) interaction. Particular attention is devoted to evaluate the vdW coefficients following the Slater-Kirkwood variational method, as both the ions are polarizable. Our calculated results have revealed reasonably good agreement with the available experimental data on the phase transition pressures (P t = 81, 21, 13 GPa) and the elastic properties of UX (X = S, Se, and Te). The equation of state curves (plotted between V (P)/V (0) and pressure) for both the NaCl-type (B1) and CsCl-type (B2) structures obtained by us are in fairly good agreement with the experimental results. The calculated values of the volume collapses ( V (P)/V (0)) are also closer to their observed data. The variations of the second-and third-order elastic constants with pressure have followed systematic trends, which are almost identical to those exhibited by the measured and observed data in other compounds of the NaCl-type structure family.

Study of electronic and elastic properties of β‐HgS under high pressure via first‐principles calculations

“…It is noticed that C 11 , C 12 and B increase linearly with pressure, while C 44 decreases linearly with pressure. Similar behavior was observed in UX (X=S, Se and Te) [23].…”

Elastic and thermodynamical properties of cubic (3C) silicon carbide under high pressure and high temperature

“…We express the molecular force in the absence of the Lorentz effective field [19][20][21][22][23][24][25][26].…”

“…(106) is the thermal phonon pressure. The temperaturedependent second-order elastic constants C ij are derived from the dynamical matrix of modified Rigid Shell model [19][20][21][22][23][24][25][26][35][36][37][38][39][40][41][42] and the method of long waves as Herein, the potential energy incorporates the long-range Coulomb with charge transfer interactions, covalent nature of bonds, and short-range overlap repulsive interaction up to second-neighbour as well charge dipole-dipole and charge dipole-quadruple (van der Waals) interaction.…”

“…While discussing the mechanical and thermodynamical properties, the lattice dynamical model based on charge transfer interactions has been found successful [19][20][21][22][23][24][25][26]. The overlap repulsion potential (extended up to second-neighbour ions) is based on Hafemeister and Flygare [27].…”

The elastic and thermodynamic properties of antiperovskites: MCNi3

“…Motivated from such a realistic and qualitative representation of the interionic and the versatile applicability of MRIM in depicting the cohesive and physical properties of solids and alloys (Singh [37] and Varshney et al [38]), we thought it is pertinent to apply this model, probably for the first time, in exploring the elastic and thermodynamic properties of MCNi 3 (M = Zr, Cd, Ag, Tc, Mg, Zn). The interaction potential of the MRIM is described in Section 2.…”