Enhanced thermoelectric properties of AgSbTe₂ obtained by controlling heterophases with Ce doping

We report the enhanced thermoelectric properties of Ce-doped AgSbTe₂ (AgSb_1-xCe_xTe₂) compounds. As the Ce contents increased, the proportion of heterophase Ag₂Te in the AgSbTe₂ gradually decreased, along with the size of the crystals. The electrical resistivity and Seebeck coefficient were dramatically affected by Ce doping and the lattice thermal conductivity was reduced. The presence of nanostructured Ag₂Te heterophases resulted in a greatly enhanced dimensionless figure of merit, ZT of 1.5 at 673 K. These findings highlight the importance of the heterophase and doping control, which determines both electrical and thermal properties.