Effects of Y2O3 on the microstructure and electrical properties of Pr-ZnO varistors

Effects of Y2O3 contents on the microstructure and electrical properties of Pr6O11-based ZnO varistor have been studied. The varistor voltage (V1mA) and the nonlinear exponent (α) increased with increasing Y2O3 contents, whereas the dielectric constant decreased. Y-rich phase segregated at nodal points in grain boundaries. The average grain size decreased with increasing Y2O3 content. The specimen with 4.0 mol% Y2O3 sintered at 1285 ∘C exhibited the highest nonlinear exponent (α = 77) with the dielectric constant, ~352 at 1 kHz.