MUON DIFFUSION AND TRAPPING IN PROTON CONDUCTING OXIDES

Trapping as a main feature of proton diffusion in proton conducting ox ides was investigated by means of muon spin relaxation measurements, w ith the positive muon as tracer. In Sc-doped SrZrO3, a system with rep resentative physicochemical properties and favourable nuclear magnetic moments, the muons are trapped at single Sc ions at a distance of 2.4 9 Angstrom with a binding energy of 0.2 eV, in accordance with previou s proton results. The muons form muoxide ions which are directed along the bisector of two oxygen-oxygen connection lines. The mu SR spectra could quantitatively be described in terms of a two-state model for t he muon diffusion comprising random sequences of trapping events and f ree diffusion periods. (C) 1998 Elsevier Science B.V. All rights reser ved.