Isotopic effect of proton conductivity in gadolinium sesquioxide

Abstract

Due to the higher hydrogen solubility and diffusivity, gadolinium sesquioxide (Gd2O3) could be expected as a proton conductive material. In this study, monoclinic Gd2O3 was used to evaluate the possible proton conductivity in Ar (σAr), Ar+4% H2 (σH2), Ar+4% D2 (σD2), Ar+H2O (σH2O), Ar+D2O (σD2O), and O2 (σO2) atmospheres in the temperature range from 500°C to 1000°C, to understand its possible application in the DT fuel system of a nuclear fusion reactor. At all temperatures, the conductivity σD2 was lower than that of the σH2. Similarly, the σD2O was always lower than that of the σH2O. The isotope dependence was appreciable at higher temperatures, indicating that Gd2O3 is a proton-conductive oxide at elevated temperatures. However, much improvement is required for the use of Gd2O3 in the DT fuel recovery, analysis, and purification system of fusion reactors.