High Seebeck Coefficient Amxp(2) (A = Ca And Yb; M, X = Zn, Cu And Mn) Zintl Phosphides As High-Temperature Thermoelectric Materials

Resistivity (rho), Seebeck coefficient (alpha) and thermal diffusivity of the title compounds CaZn2P2, YbZn2P2, YbCuZnP2 and YbMnCuP2 are measured over a temperature range 300-1000K to evaluate the thermoelectric potential of these materials. The temperature dependence of. and a of these light weight and less explored Zintl phosphides is similar to that of a degenerate semiconductor. While the electrical transport properties. and a are strongly composition dependent, thermal conductivity (kappa) calculated from thermal diffusivity is remarkably low in the range 1.1-2.5W m(-1) K-1 at 1000 K. Room-temperature Hall resistance measured on selected samples suggests that holes dominate in the transport. The best composition appears to be YbZnCuP2 which has the combination of rho similar to 2.4m Omega cm, alpha similar to 160 mu V K-1 and kappa similar to 1.7W m(-1) K-1 at 1000K resulting in a ZT value of similar to 0.6.