Enhanced thermoelectric performance of Zn-doped oxyselenides: BiCu1−x Zn x SeO

Abstract

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 (600–700 nm) with nanostructured ZnSe secondary phase. Our results reveal that Zn doping can lead to a large change in the carrier concentration (from 0.036 × 1020 cm−3 to 1.50 × 1020 cm−3), thus resulting in an increased electrical conductivity of three orders of magnitude at room temperature. The highest power factor of 4.21 µWcm−1K−2 at 873 K 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 873 K in the BiCuSeO oxyselenides by the 10% Zn doping, which makes Zn-doped BiCuSeO to be a promising candidate for thermoelectric applications.