Dielectric relaxation properties of perovskite-pyrochlore biphase ceramics

摘要

The structure and dielectric relaxation properties of (1-x)NaNbO_3-xBiCrO_3 (0.1 ≤ x ≤ 0.5) composite ceramics with perovskite-pyrochlore biphase were studied. The coexistence of cubic perovskite and a cubic pyrochlore structure was characterized. A lack of mutual solubility between the two phases was observed. Biphase ceramics with x=0.3 exhibited dielectric relaxation behavior with a diffuse-like phase transition. Pyrochlore-rich biphase ceramics with x=0.4 exhibit dielectric relaxor-like behavior. The biphase ceramics have high dielectric constants, because of the reorientation of the dipoles and the formation of barrier layers at the grain boundaries.