Effect of Order-Disorder Transition on Thermal Conductivity of Gd2Zr2O7 Ceramics

Abstract

Abstract Rare earth zirconates have been considered as promising candidates for thermal barrier coatings, with extremely low thermal conductivity which is usually attributed to their unique pyrochlore/fluorite structure. In order to investigate the different influence of pyrochlore and fluorite structure on thermal conductivity, Gd2Zr2O7 ceramics with pyrochlore and fluorite structure were prepared separately by controlling the sintering temperature, and the thermal conductivities of the samples sintered at different temperatures were measured and investigated. The results show that the structure of Gd2Zr2O7 changes gradually from pyrochlore to fluorite as the sintering temperature increases from 1450°C to 1600°C, accompanying with a thermal conductivity decreasing first and then increasing. The minimum value of thermal conductivity appears on the sample with pyrochlore structure nearby the phase transition temperature range, rather than that with fluorite structure. Other than the transition of structure, structural distortion in the lattice approaching phase transition may lead to a distinct decrease of thermal conductivity.