Pressure Dependence of Structural and Elastic Properties of Na₂O: First-Principles Calculations

Abstract

The effect of high pressures, up to 40 GPa, on the structural and elastic properties of sodium oxide in cubic structure (c-Na2O) were investigated by first-principles calculations. The generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) functional was employed in the calculations. The calculated structural and elastic properties at zero pressure are consistent with the available results. The pressure dependence of structural and elastic properties was presented and discussed in detail. Under pressure, the elastic constants satisfy the Born criteria, indicating that c-Na2O is mechanically stable. Moreover, other elastic properties such as bulk modulus (B), shear modulus (G), and Young's modulus (E) under pressures were analyzed. Furthermore, the B/G values tend to increase with the increasing pressure, which means that pressure can improve the ductility of c-Na2O.