The incorporation and migration of protons in Nd-doped BaCeO3

Abstract

A detailed study of protonic conductivity in Nd-doped BaCeO3 is made using water-uptake and galvanic-cell measurements to supplement the conductivity results. Samples were pretreated at 900°C at different PH2O atmospheres and the conductivity measured with a frozen-in proton concentration. Isotope effect (D2O versus H2O) measurements were also made. The results show that interstitial protons enter the lattice as compensators for the dopant, replacing oxygen-ion vacancies, and migrate by hopping between adjacent O2- ions with a low migration energy of 0.54 eV. Comparison with other acceptor-doped perovskite oxides is made in order to better understand the origin of the high protonic conductivity in this material.