High-temperature thermoelectric properties of W-substituted CaMnO_3

摘要

The thermoelectric properties of W-substituted CaMn_(1-x)W_xO_(3-δ) (x = 0.01, 0.03; 0.05) samples, prepared by soft chemistry, were investigated from 300 K to 1000 K and compared to Nb-substituted CaMn_(0.98)Nb_(0.02)O_(3-δ). All compositions exhibit both an increase in absolute See-beck coefficient and electrical resistivity with temperature. Moreover, compared to the Nb-substituted sample, the thermal conductivity of the W-substituted samples was strongly reduced. This reduction is attributed to the nearly two times greater mass of tungsten. Consequently, a ZT of 0.19 was found in CaMn_(0.97)W_(0.03)O_(3-δ) at 1000 K, which was larger than ZT exhibited by the 2% Nb-doped sample.