First principle study of optoelectronic and thermoelectric properties of magnesium based MgX₂O₄ (X = Sb, Bi) spinels

The structural, electronic, optical, and thermoelectric properties of MgX₂O₄ (X ​= ​Sb, Bi) are addressed by density functional theory (DFT). The thermodynamic stability is confirmed by means of formation energy. Band structure calculation by modified Becke and Johnson potential (TB-mBJ) reveals MgSb₂O₄, and MgBi₂O₄ possess indirect band gaps of 1.49 ​eV, and 2.35 ​eV. Optical properties are analysed by dielectric constants, absorption, refraction, refractive index etc. Further, the thermoelectric performance of these materials is explored by electrical conductivity, thermal conductivity, power factor, Seebeck coefficient, and figure of merit (ZT). The magnitude of ZT at room temperature are 0.74 and 0.72 for MgSb₂O₄ and MgBi₂O₄ led that these materials are remarkable for thermoelectric devices.