A detailed study of protonic conductivity in Nd-doped material was performed by using water-uptake and galvanic-cell measurements to supplement the conductivity results. The samples were pre-treated at 900C, under various partial pressures of H2O, and the conductivity was measured with a frozen-in proton concentration. Isotope effect measurements were also carried out. The results showed that interstitial protons entered the lattice as compensators for the dopant, replaced O-ion vacancies, and migrated by hopping between adjacent O2- ions; with a migration energy of 0.54eV.

J.F.Liu, A.S.Nowick: Solid State Ionics, 1992, 50[1-2], 131-8