Effect of Sr - Transition Metal Substitution on Electronic and Mechanical Properties of Mg2 Si: A DFT Study

Abstract

Recently, magnesium alloys have attracted scientific interest due to their technological importance in thermoelectric, piezoelectric, photo-voltaic and infrared photonics applications. The electronic and elastic properties of MgXSi (X = Mg, Sr) compounds were investigated in this work, using the density functional theory (DFT) with pseudo-potential plane-waves (PPW) approach as implemented in Quantum Espresso code. The results of the elastic constants of Mg₂Si are in agreement with the previous theoretical
results and favourably compared with experimental data. The electronic band structures of these semiconductors were calculated to give narrow indirect and direct band gaps of Mg₂Si and MgSrSi, respectively. Our results show that the two compounds are
mechanically stable. The Pugh’s ratio, B/G, indicated that Mg₂Si and MgSrSi are brittle and ductile in nature. The estimated anisotropy parameter, A, shows that Mg₂Si has a higher degree of elastic isotropy in comparison to MgSrSi. Three-dimensional (3D) projection of Young’s modulus and area modulus of the compounds was presented.

Keywords: Electronic structure, Elastic constants, Mechanical properties, Mg₂Si, MgSrSi.

PACS: 31.15.A-, 62.20.F-, 71.55.-i, 71.20.Be.