Phase formation, microstructure development and thermoelectric properties of (ZnO)(k)In2O3 ceramics

Abstract : The (ZnO)(k)In2O3 system is interesting for applications in the fields of thermoelectrics and optoelectronics. In this study we resolve the complex homologous phase evolution with increasing temperature in polycrystalline ceramics for k = 5, 11 and 18 and its influence on the microstructural development and thermoelectric properties. The phase formation at temperatures above 1000 degrees C is influenced by the local ZnO-to-In2O3 ratio in the starting-powder mixture. While the equilibrium phase for k = 5 is formed directly after sintering at 1200 degrees C, the formation of the k = 11 and k =18 equilibrium phases proceeds at higher temperatures by diffusion between the initially formed phases, the lower k Zn5In2O8/Zn7In2O10 and the higher k ZnkIn2Ok+3 (9 < k < infinity)Such phase formation affects the sintering and grain growth, and consequently, with the degree of structural and compositional homogeneity, also the thermoelectric characteristics of the (ZnO)(k)In2O3 ceramics. (C) 2017 Elsevier Ltd. All rights reserved.