Effect of Ball-Milling Conditions on Thermoelectric Properties of Polycrystalline CuGaTe₂

Abstract

CuGaTe₂ has a large thermoelectric (TE) figure of merit (ZT) at high temperatures, i.e., ZT = 1.4 at 950 K. However, at lower temperatures, the ZT values are smaller. One reason for this is that CuGaTe₂ has a high lattice thermal conductivity (κ_lat) at lower temperatures. One known method for reducing κ_lat is manipulating the microstructure of the bulk material. Therefore, herein, the grain-size effect on the TE properties of CuGaTe₂ bulk samples produced by ball milling and hot pressing was investigated. Although κ_lat decreased with grain size, a simultaneous decrease in the Seebeck coefficient occurred, leading to no overall improvement in ZT.