Thermal conductivity of Zn4-xCdxSb3 solid solutions

beta-Zn4Sb3 was recently identified at the Jet Propulsion Laboratory as a new high performance p-type thermoelectric material with a maximum dimensionless thermoelectric figure of merit ZT of 1.4 at a temperature of 673K. A usual approach, used for many state-of-the-art thermoelectric materials, to further improve ZT values is to alloy beta-Zn4Sb3 with isostructural compounds because of the expected decrease in lattice thermal conductivity. We have grown Zn4-xCdxSb3 crystals with 0.2 less than or equal to x<1.2 and measured their thermal conductivity from 10 to 500K. The thermal conductivity values of Zn4-xCdxSb3 alloys are significantly lower than those measured for beta-Zn4Sb3 and are comparable to its calculated minimum thermal conductivity. A strong atomic disorder is believed to be primarily at the origin of the very low thermal conductivity of these materials which are also fairly good electrical conductors and are therefore excellent candidates for thermoelectric applications.