Local Structure and Mixed Proton-Hole Conduction in Y and Al-Doped BaZrO₃

Enhancing proton-hole mixed conduction is one of the promising methods to improve the cathode performance of proton-conducting fuel cells. In this study, Al-doping is conducted to enhance the hole conduction in Y-doped BaZrO 3 . The relationship between the defect structure around Al and the electrical conductivity is investigated. 27 Al NMR results indicated the formation of more than one oxygen vacancy around Al and the clustering of the acceptors. The electrical conductivity shows dominant proton conduction below 600ºC while other charge carriers, such as oxygen vacancies and electron holes, dominate at 800ºC. The Al-doping affects the formation of the defects but shows negligible influence on the dominant charge carriers at lower temperatures.