Enhanced thermoelectric performance of Zn-doped oxyselenides: BiCu 1− x Zn x SeO: Enhanced thermoelectric performance of Zn-doped oxyselenides

High-performance thermoelectric BiCuSeO ceramics have been prepared by solid state reaction combined with plasma activated sintering (PAS). Phase compositional and microstructural studies indicate composites having refined grain sizes (600-700nm) with nanostructured ZnSe secondary phase. Our results reveal that Zn doping can lead to a large change in the carrier concentration (from 0.036x10(20)cm(-3) to 1.50x10(20) cm(-3)), thus resulting in an increased electrical conductivity of three orders of magnitude at room temperature. The highest power factor of 4.21 mu Wcm(-1)K(-2) at 873K has been achieved by 10% Zn doping. On the other hand, the lattice thermal conductivity has been suppressed significantly due to refined grains, point defects and the nano-inclusions of ZnSe phase. The dimensionless figure of merit (ZT) could reach up to 0.90 at 873K in the BiCuSeO oxyselenides by the 10% Zn doping, which makes Zn-doped BiCuSeO to be a promising candidate for thermoelectric applications.