Thermoelectric properties of Mg doped p-type BiCuSeO oxyselenides

We report on the effect of Mg doping on the thermoelectric properties of p-type BiCuSeO oxyselenide, with layer structure composed of conductive (Cu2Se2)(2) layers alternately stacked with insulating (Bi2O2)(2+) layers. The substitution of Bi3+ by Mg2+ leads to an enhancement of the electrical conductivity and a decrease of the thermal conductivity. Coupled to high Seebeck coefficients, ZT at 923 K is increased from 0.45 for pristine BiCuSeO to 0.67 for Bi0.95Mg0.05CuSeO. However, the efficiency of Mg doping in the insulating (Bi2O2)(2+) layer is low, and this doping only leads to a limited increase of the hole carriers concentration. Therefore Mg doped BiCuSeO has relatively low electrical conductivity which makes its thermoelectric figure of merit much lower than that of Ca, Sr and Ba doped BiCuSeO. (C) 2012 Elsevier B.V. All rights reserved.