Synthesis and high-temperature thermoelectric properties of Ni3GaSb and Ni3InSb

Ni₃GaSb and Ni₃InSb were successfully synthesized by the direct reaction of Ni and GaSb or InSb. The XRD patterns and the lattice parameters of these compounds were in good agreement with the literature data. The Seebeck coefficient (S), the electrical resistivity (ρ), and the thermal conductivity (κ) of Ni₃GaSb and Ni₃InSb were examined in the temperature range from room temperature to 1073 K. Both compounds indicated metal-like characteristics. The power factor (S²ρ⁻¹) values increased with temperature and reached maximum at 1073 K. The κ and the dimensionless figure of merit ZT of both samples increased with temperature. The maximum values of the ZT of Ni₃GaSb and Ni₃InSb were obtained at 1073 K to be 0.022 and 0.023, respectively.     

Synthesis and thermal conductivities of ZnIn2Te4 and CdIn2Te4 with defect-chalcopyrite structure

ZnIn₂Te₄ and CdIn₂Te₄ have a defect-chalcopyrite tetragonal crystal structure with structural vacancies. In order to investigate the effects of vacancies on the lattice thermal conductivity (κ_lat), single phase samples of ZnIn₂Te₄ and CdIn₂Te₄ were synthesized and their κ_lat values were examined in the temperature range from room temperature to 850 K. The κ_lat data for ZnIn₂Te₄ and CdIn₂Te₄ were compared with those of Zn- and Cd-series chalcopyrite compounds with no vacancies. The results revealed that the presence of vacancies alone in the defect-chalcopyrite structure does not result in effective phonon scattering.