Estimation of expansion of Ce_1-xRe_xO_2-δ under various atmospheres by high-temperature XRD

Abstract

Phase relationship and lattice constants of Ce_1-xRe_xO_2-δ(Re=Gd, Sm, Y) at high temperatures under various gas atmospheres were analyzed by using high temperature X-ray diffraction. Even though CaF₂ type cubic structure was maintained under H₂/H₂O gas mixture at temperatures less than 1000 °C, lattice expansion was observed under reductive atmospheres at temperatures more than 700 °C. By using oxygen nonstoichiometry data measured by thermogravimetry, the relationship between δ and lattice constants was estimated. It was revealed that lattice constant increased with increase of δ, however there observed was difference of expansion behavior by doping element and its amount.