Dielectric relaxation properties of perovskite-pyrochlore biphase ceramics

The structure and dielectric relaxation properties of (1-x)NaNbO3-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. (C) 2005 American Institute of Physics.