Grain oriented ceramics of layer-structured n-type oxide for high thermoelectric performance

Homologous compounds of (ZnO)(m)In2O3(M: integer) with layered structures show comparatively high thermoelectric properties as oxide materials, and we have reported that the in-plane (hexagonal ab plane) conductivity is 10 times as large as the cross-plane conductivity (hexagonal c-axis). To apply such crystals with structural anisotropy to thermoelectric materials, we need to give thermal gradient in the direction of highest conversion efficiency. We fabricated textured (ZnO)(5)In2O3 polycrystals by the RTGG method which includes in-situ reaction of template ZnO particles with plate-like shape and fine In,03 particles, and thermoelectric properties were evaluated. Three times as high figure of merit Z (= C alpha(2)/kappa) as that of the non-textured specimen was achieved by texturing. This time we report the accomplishment of higher thermoelectric properties by textured polycrystals of (ZnO)(5)In0.97Y0.03O3.