It is found that the proton is strongly absorbed in heavily Sc-doped ${\mathrm{SrTiO}}_3$. Neutron-diffraction measurements were performed using single crystals. The O-H distance is found to be about 1.2 Å and the proton concentration is estimated to be about 2 mol % for ${\mathrm{SrTi}}_{0.98}$${\mathrm{Sc}}_{0.02}$${\mathrm{O}}_3$. Protonic conduction was observed in Sc-doped ${\mathrm{SrTiO}}_3$ by ac-conductivity measurements in wet air, while the hole conductivity was observed in dry air. The proton is bound by the oxygen ion as if the proton makes the hydrogen bond between two oxygen ions, which might be responsible for the high protonic conductivity in this material. © 1996 The American Physical Society.

• Received 6 June 1996

DOI:https://doi.org/10.1103/PhysRevB.54.15795