Thermoelectric properties of β-Zn4Sb3 doped with Sn

We have tried to dope β-Zn₄Sb₃ with Sn for the purpose of the p-type doping and the enhancement of phonon scattering, which further improve the thermoelectric properties of βZn₄Sb₃. Polycrystalline samples doped with Sn were prepared by the spark plasma sintering method. Although no other phase was observed except for β-Zn₄Sb₃ in Sn-doped samples up to 3%, their lattice constants were not at all changed from that of bulk β-Zn₄Sb₃, indicating that Sn was not unfortunately substituted for Sb. These results suggest that microcrystals of Sn is dispersed in grain boundary regions of β-Zn₄Bb₃. The Seebeck coefficient was almost unchanged, and the electrical conductivity was slightly decreased by doping β-Zn₄Sb₃ with Sn, indicating that Sn does not act as a dopant. On the other hand the thermal conductivity was lowered from 8.66mW/cmK of the non-doped sample to 6.88mW/cmK of the 3% Sn-doped sample at room temperature. This lowering of the thermal conductivity was considered to be due to the point defect phonon scattering induced by inclusions of Sn