Thermoelectric properties of KCaF3

Using first-principles calculations based on density functional theory (DFT) with generalized gradient approximation (GGA), the electronic and thermoelectric properties of KCaF3 are calculated. The electronic structure calculated with GGA shows that KCaF3 is an insulator. The thermoelectric properties of KCaF3 are computed as a function of chemical potential t and charge carrier concentrations (10(18)-10(22)cm(-3)). Both hole and electron doping decrease the absolute value of Seebeck coefficient. The calculated power factor shows that p-type KCaF3 has a larger power factor at the optimized charge carriers. The maximum figure of merit (ZT) occurs around 10(21)cm(-3) hole carrier concentrations and the largest value of ZT similar to 0.7 is achieved at 800 K. When KCaF3 is doped with electron, the maximum ZT occurs around 10(20)cm(-3) and the largest value of ZT at 800 K is about 0.4. Hence, high ZT in KCaF3 is possible at high hole carrier concentrations as compared with electron carrier concentrations. Compared with n-type KCaF3, p-type KCaF3 has good thermoelectric properties, which are attributed to larger effective mass and low thermal conductivity of holes.