Doping effects on complex perovskite Ba_3Ca_(1.18)Nb_(1.82)O_(9-δ) intermediate temperature proton conductor

摘要

In this work, the effects of Ce doping on the Ca and Nb ions in complex perovskite (BCN18) proton conductor have been evaluated. It has been found that cerium ions can be doped into both the Ca and Nb sites to form a single-phase complex perovskite structure when the sintering temperature is 1550 ℃ Ce ions substituted with Nb ions enhances the electrical conductivity, especially the grain boundary conductivity. The highest conductivity has been obtained for a composition of Ba_3Ca_(1.18)Nb_(1.62)Ce_(0.2)O(9-δ), possessing a conductivity of 2.69 x 10~(-3) Scm~(-1) at 550 ℃ in wet H_2, a 78% enhancement compared with BCN18 (1.51 x 10~(-3) S cm~(-1)). The chemical stability tests show that Ce-doped BCN18 samples remain single phase after treated either in boiling water for 7 h or in pure CO_2 for 4h at 700 C. This work has demonstrated a new direction in developing intermediate temperature proton conducting materials that possess both high conductivity and good stability.