Enhanced thermoelectric properties of the hole-doped Bi2−xKxSr2Co2Oy ceramics
In this paper, the influence of K element doping on the thermoelectric properties of the [Formula: see text] (x = 0.00, 0.05, 0.10, 0.15, and 0.20) samples prepared by the solid-state reaction method were investigated from 333 K to 973 K. It was shown that due to the p-type K doping the electrical resistivity of the doped sample can be reduced remarkably as compared with the undoped sample, especially for the optimum doped sample [Formula: see text]. The Seebeck coefficients of the K doped samples have only a slight decrease as compared with the undoped sample. As a result of the remarkable reduction of the electrical resistivity the power factor of the doped sample have a significant improvement. The thermal conductivity of the samples is depressed due to the defects caused by K doping. As an overall result, the dimensionless figure of merit (ZT) of the [Formula: see text] sample reaches a maximum value of 0.3 at 973 K, being 93% higher than that of the undoped sample.