Exploration of magnesium based MgX₂O₄ (X = Rh, Bi) spinels for thermoelectric applications using density functional theory (DFT)

By using WIEN2k code, we investigated the mechanical and thermoelectric properties of magnesium based MgX₂O₄ (X = Rh and Bi) spinels. To compute the mechanical behavior of MgX₂O₄ (X = Rh and Bi), the Perdew-Bruke-Ernzerhof (PBEsol) flavor of generalized gradient approximation is used. From structural optimization, ground state lattice constant (a0) show a comparable with the previously evaluated theoretical and experimental values. The Born stability criterion represents that the investigated spinels are stable in the cubic phase and their ductile behaviors are observed by calculating Pugh’s ratio as well as Poisson ratio. Besides, thermodynamic behavior is concluded in terms of the Debye temperature. To investigate the electronic and thermoelectric behavior, the modified Becke and Johnson (mBJ) potential is employed. Finally, we investigated the thermoelectric behavior to represent the importance of studied spinels in thermoelectric appliances by calculating the figure of merit (ZT). High values of the See-beck coefficient and ZT at room temperature explores the potential of the studied spinels in thermoelectric devices.