Beneficial effect of high pressure and double-atom-doped skutterudite compounds Co4Sb11.5−xTe0.5Snx by HPHT

Double-atom-doped polycrystalline skutterudite compounds Co4Sb11.5−xTe0.5Snx (x = 0.1, 0.2 and 0.3) has been prepared successfully by high pressure and high-temperature (HPHT) method. The method can dope Te and Sb atoms in skutterudite crystal structure to substitute Sb-atom simultaneously. The thermoelectric properties including Seebeck coefficient, electrical resistivity and thermal conductivity were studied at room temperature. The experimental data were as we would expect: with the synthesis pressure rise, a larger absolute Seebeck coefficient was maintained, which was likely due to the large effective mass arising from the doped atoms. Moreover, the lattice thermal conductivity of Co4Sb11.5−xTe0.5Snx was observed to decrease monotonously with the pressure increasing at room temperature, which was attributed to the high densities of grain boundaries and point defects in the Sb cages. Comparing with other methods, HPHT could shorten the synthesis time from several days to half an hour. Results indicated that the method of HPHT combined with double-atom-doping could optimize electrical and thermal transports in a relatively independent way, and the excellent properties gained at high pressure can be partially maintained to ambient pressure.