Site selectivity of dopants in BaZr _1-yM _yO _3-δ (M = Sc, Y, Sm, Eu, Dy) and measurement of their water contents and conductivities

The site selectivity of Sc, Y, Sm, Eu, and Dy in doped BaZrO ₃ was investigated. The measurement of water contents and conductivities of the samples were performed. The results revealed that for doping rare-earth cations into BaZrO ₃, all the examined dopants mainly occupied B-site, while a partial A-site occupation of Sm and Eu was significantly recognized. Sm and Eu are considered to be more amphoteric for doping into BaZrO _3. The concentration of hydroxide ions in the sample of BaZr _0.8Dy _0.2O _3-δ hydrated in wet Ar was obviously higher than that hydrated in wet O ₂ at the same humidification level. The bulk conductivity of BaZr _0.8Dy _0.2O _3-δ in wet Ar or H ₂ is higher than that in a dry one, indicating the generation of protonic conductivity of BaZr _0.8Dy _0.2O _3-δ. The strong dependence of conductivity on partial pressure of oxygen was also recognized. The bulk conductivities of BaZr _0.8Dy _0.2O _3-δ in wet Ar and H ₂ were comparable to that of BaZr _0.8Y _0.2O _3-δ.