Power factors of late rare earth-doped Ca3CO2O6 oxides

摘要

Polycrystalline samples of (Ca1-xRx)(3)Co2O6 with R = Gd, Tb, Dy and Ho at x = 0-0.1 were synthesized and the effects of rare earth substitution on their thermoelectric properties were investigated. In the high-temperature region, the rare earth substitution resulted in an increase in the Seebeck coefficients (S), and the S values increased with decreasing ionic radius of rare earth elements in the order Gd3+ > Tb3+ > Dy3+ > Ho3+. In contrast, the influence of rare earth substitution on the electrical resistivity was small. The high-temperature power factor was thereby improved by the late rare earth substitutions, particularly those with Ho3+ for Ca2+. For the Ho-doped samples (x <= 0.05), the power factor was significantly improved by increasing Ho concentration. (c) 2006 Elsevier Ltd. All rights reserved.