Deficiency-induced absence of topological insulator behavior in antiperovskite Dirac metal oxide Sr3-x SnO: a DFT study

Abstract

This study focuses on Sr3SnO (SSO), an antiperovskite Dirac metal-oxide (ADMO), that exhibits improved and enhanced physical properties when decreasing the number of Strontium (Sr) atoms in the crystal structure Sr3-xSnO. Stability and electronic properties calculations were performed using the density functional theory (DFT). Furthermore, transport and thermoelectric properties were determined by solving the Boltzmann transport equation implemented in BoltzTraP code. We report a topological insulator behavior when applying spin–orbit coupling (SOC) to pristine SSO. This behavior became absent when Sr concentration decreased. Moreover, when increasing oxygen concentration (Sr3SnO2), we reveal an improvement in the system’s stability. Electrical conductivity enhanced, for both Sr deficient SSO and for oxygen excess, reaching a value of 1.8×10201/Ω.m.s for x = 1. In addition, we show that Sr3-xSnO possesses both p-type and n-type nature, depending on the value of Sr deficiency concentration x, which makes this compound a suitable candidate for a thermoelectric generator (TEG) module.