Thermoelectric properties of Cd3-xAxTeO6 (A = In3+, La3+ and Bi3+) ceramics

Perovskite oxide Cd3TeO6 was electron.-doped by the introduction of oxygen vacancies and substitution of trivalent cations, In3+, La3+ and Bi3+. Their electric properties were. investigated and compared with that of undoped Cd3TeO6. Negative temperature dependence of resistivity was observed in undoped, air-sintered Cd3TeO6. The resistivity of Cd(3-x)A(x)TeO(6) (A = In3+, La3+ and Bi3+) showed a metallic behavior with very slight temperature dependence. Indium-doped samples gave a low resistivity, which were decreased by more than three orders of magnitudes than that of air-sintered, undoped Cd3TeO6. The negative Seebeck coefficient and Hall coefficient obtained from all samples indicate that electrons are the charge carriers.. The absolute Seebeck coefficients values of doped samples are decreased by 5 similar to 10 times than that observed in undoped Cd3TeO6. Fortunately, the resistivity of indium-doped samples is low enough to provide a good thermoelectric power factor, and the optimum value of Cd2.97In0.03TeO6 was calculated as 1.35x10(-4) Wm(-1) K-2. This result is close to that of the current best n-type perovskite thermoelectric material Ba0.4Sr0.6PbO3.