Dielectric relaxation of protonic defects in hydrated and dehydrated SrZrO3:Yb

Dielectric relaxations of proton conductor Yb-doped SrZrO3 have been measured as a function of temperature and frequency in different pretreatments with water vapor. Well defined two relaxation peaks were observed in the compounds doped with more than 1 mol% of Yb irrespective of annealing in WET (hydrate) or DRY (dehydrate) conditions. These two relaxations can be assigned to reorientations of Yb-proton dipole at an isolated [YbO6]-octahedron and at a [YbO6]–[YbO6]–... cluster in the SrZrO3 crystal (i.e. effectively negative charged Yb and positive charged proton). By DRY pretreatment, the magnitude of the dipole strength was almost fixed for the isolated Yb-proton dipole, while the magnitude became significantly decreased for the dipole associated with the Yb-cluster. It shows the proton associated with the isolated Yb is more stable than that with the Yb-cluster.