Thermal conductivity of Zn_(4-x)Cd_xSb_3 solid solutions

摘要

beta -Zn_4Sb_3 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 14 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 -Zn_4Sb_3 with isostructural compounds becasue of the expected decrease in lattice thermal condcutivity. We have grown Zn_(4-x)Cd_xSb_3 crystals with 0.2<=x<1.2 and measured their thermal conductivity from 10 to 500K. The thermal conductivity values of Zn_(4-x)Cd_x Sb_3 alloys are significantly lower than those measured for beta -Zn_4Sb_3 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 arre also fairly good electrical conductors and are therefore excellent candidates for thermoelectric applications.