Thermoelectric properties of semiconductorlike intermetallic compounds TMGa3 (TM=Fe, Ru, and Os)

Abstract

Transport properties of polycrystalline TMGa3 (TM=Fe, Ru, and Os) compounds are reported in the temperature range 313K<T<973K. These compounds exhibit semiconductorlike behavior with relatively high Seebeck coefficient and electrical resistivity. Hall carrier concentrations at room temperature are reported in the range of 1017–1018cm−3. Seebeck coefficient measurements indicate that FeGa3 and OsGa3 are n-type material at the operating temperature; on the other hand, the Seebeck coefficient of RuGa3 changes its sign rapidly from large positive value to large negative value around 450K. The thermal conductivity of these compounds is estimated to be 3.5W∕mK at room temperature and decreases with increasing temperature. The absolute value of the lattice thermal conductivity for FeGa3, RuGa3, and OsGa3 is 3.5W∕mK at room temperature, and decreases down to 2W∕mK at high temperature. The resulting thermoelectric figure of merit ZT at 945K for RuGa3 reaches 0.18.