GRAIN BOUNDARY RESISTIVITY IN YTTRIA-STABILIZED ZIRCONIA

摘要

Three topics pertaining to the effect of grain size d on the grain boundary resistivity ρ_b in yttria-stabilized zirconia are considered: (a) the pertinent literature, (b) our recent isothermal annealing experiments and (c) development of a new model based on the effect of an electric field on grain growth. The grain size dependence of the bulk resistivity determined from the annealing tests was in reasonable accord with those in the literature from impedance spectroscopy. Two regimes occurred in the grain size dependence of the bulk resistivity, one for d > ～0.4μm, the other for smaller grain sizes. Employing the brick layer model, the grain boundary resistivity in the latter regime was approximately an order of magnitude larger than that within the grain interior. Our new model gave values for the space charge potential and grain boundary energy in accord with expectations and measurements. It is concluded that the space charge is the major factor responsible for the grain boundary resistivity.