Rb(Zn,Cu) 4 As 3 as a New High-Efficiency Thermoelectric Material.

The thermoelectric performance of RbZn 4- x Cu x As 3 crystallized in the KCu 4 S 3 -type structure was investigated. Samples were synthesized via solid-state reactions, followed by hot pressing. Hole carriers were doped by substituting Zn with Cu until x = 0.02, resulting in an increase of the power factor from 0.049 to 0.52 mW/mK 2 at T = 797 K. The lattice thermal conductivity was substantially low, with a value of 1.61 W/mK at T = 312 K, independent of doping. This can be attributed to the large vibration of the Rb atoms, as demonstrated by the neutron diffraction analysis. The maximum dimensionless figure of merit, ZT, was 0.53 at T = 797 K, representing the highest value for the 143-Zintl compounds. The result indicated that the 143-Zintl compounds could be a new class of high-performance thermoelectric materials.