Preparation of Phase Diagram of Ba_1-xSr_xZrO₃ by X-ray Diffraction and Thermal Analyses for Exploration of New Proton Conductor

Abstract

In order to develop new proton conductor, phase diagram of Ba_1-xSr_xZrO₃ with high reliability has been established by combination of results of X-ray diffraction measurements at various temperatures and thermal analyses. The variation of crystal structures revealed by X-ray diffraction measurements at various temperatures agreed with phase boundary observed by DSC and dilatometry. The two phase coexistence region according to the first order phase transition was clarified from the variation of X-ray diffraction peak intensity of tetragonal and body-centered orthorhombic phases. Among Ba_1-xSr_xZrO₃, the highest conductivity was observed in Ba_0.6Sr_0.4ZrO₃, indicating that Ba_0.6Sr_0.4ZrO₃ was promising as mother phase of proton conducting oxide. Ba_0.6Sr_0.4Zr_0.9Y_0.1O_3-δ showed higher proton conductivity than so far reported BaZr_1-xY_xO_3-δ prepared with the same solution mixing method.