A quantum mechanical model was proposed for the conduction mechanism in perovskite-type oxide-based protonic conductors such as Sc-doped SrTiO3. The zero-point vibration and tunnelling motions of protons or deuterons on the O-H(D)▪▪▪O bond in the perovskite structure were investigated. In the 3-dimensional system of the O-octahedron network, 3 types of potential curve were considered for hopping or tunnelling proton motion on the O-H(D)▪▪▪O bond network. Proton sites and motion were compared with the results of neutron scattering and molecular dynamics simulations. The numerical results were used to explain the H(D)-isotope effect upon the conductivity. The optimum process of proton diffusion was studied within this theoretical approach, and the actual conduction paths were predicted and compared with experimental data for proton diffusivity in SrTiO3 and SrZrO3-based conductors.

Theoretical Approach for Protonic Conduction in Perovskite-Type Oxides. F.Matsushita, T.Sasaki: Solid State Ionics, 1999, 125[1-4], 31-7