Thermoelectric Properties of ZnO-based Thermoelectric Materials Modified with Ultrafine Heterostructures

Abstract

Incorporation of ultrafine heterostructures, inclusions and cavities, and investigated on thermoelectric performance of ZnZn_0.98Al_0.02O. Into the starting powder mixture, 10wt% of ZrO₂ fine powders or polymethylmethacrylate (PMMA) fine beads were added; both are expected to form heterogeneous ultrafinestructures as phonon scattering centers, while the latter is intended to form cavities (voids) rather than oxide particulate inclusions. Although the reduction of the thermal conductivity is the weakest for the smallest polymer beads of 0.1-0.2 μm in diameter, this sample shows remarkable enhancement of the thermopower at around 500°C, keeping the electrical conductivity virtually intact compared to the completely dense sample without the polymer beads. This sample thereby reaches the maximum power factor of 40×10^-4 W/mK², almost doubling the ZT value.