Theoretical analysis of thermoelectric performance in p-type CoSb3 based skutterudite by simultaneous partially void filling and Sn substitution

The investigation of CoSb3-based skutterudites is an important research area. Filling their structural voids and/or doping them upon substitution either at the metal or at the pnicogen sites improves the point defect scattering mechanism and enhance the thermoelectric figure of merit (ZT), thus resulting in a higher Seebeck coefficient and electrical conductivity and a lower thermal conductivity. In this work we analyze the effect of Sn substitution on the structural, electronic and thermoelectric properties of doped and partially filled CoSb3 (Ba0.5Co8Sb24-xSnx), where (x = 0, 1, 2, 3 and 4). Our calculations are performed within the fully potential-linearized augmented plane wave method (FP-LAPW) using a semi-classical Boltzmann transport theory. The theoretical analysis show that the charge balance of Ba0.5Co8Sb24-xSnx strongly depends on the substitution configuration. The Ba0.5Co8Sb23Sn composition is the most stable in terms of energy. When we examine the effect of Sn substitution on the electronic and thermoelectric properties, we find that the electronic properties are moderate and thermoelectric performance is improved. That is, the estimated dimensionless electronic figure of merit (ZT(e)) is approximately 0.67 at T = 500K for Ba0.5Co8Sb23Sn; ranking this material as a promising candidate for thermoelectric applications.