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

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.

Study on the thermal insulation property of lanthanum–cerium oxide coatings

“…Yet, hightemperature variations for instance sintering and phase transformation cause its premature failure above 1200°C. 5,6 To meet the high-temperature needs of the turbine at the entrance, researchers have strived to explore novel hightemperature thermal insulation materials, such as rare-earth cerate, 7 phosphate, 8 zirconate 9 and aluminate. [10][11][12] Among these novel high-temperature thermal insulation materials, lanthanum-cerium oxide (LCO) with defective fluorite structure is a relatively widely researched material.…”