Deficiency-induced absence of topological insulator behavior in antiperovskite Dirac metal oxide Sr_3-x SnO: a DFT study

Abstract

Abstract This study focuses on Sr 3 SnO (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 Sr 3-x SnO. 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 (Sr 3 SnO 2 ), 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1.8</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>20</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em"/> <mml:mn>1</mml:mn> <mml:mo>/</mml:mo> <mml:mi mathvariant="normal">Ω</mml:mi> <mml:mo>.</mml:mo> <mml:mi>m</mml:mi> <mml:mo>.</mml:mo> <mml:mi>s</mml:mi> </mml:math> for x = 1. In addition, we show that Sr 3-x SnO 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.