Effect of Ca substitution on phase compositions and dielectric properties of Bi_2O_3-ZnO-Nb_2O_5 pyrochlore ceramics

摘要

The phase evolution, microstructure and dielectric properties in the Ca~(2+) substituted Bi_2O_3-ZnO-Nb_2O_5 system were studied. The crystalline phases of the [Bi_(1.8)(CavZn_(1-x)_(0.2)]Zn_(0.6)Nb_(1.4))O_7 pyrochlores (0.0 0.5. As the x value increased from 0.5 to 1.0, the permittivity in the microwave range decreased from 76.4 to 75.0, the quality factor Qf value increased from 1800 to 4700 GHz, and the TCF value shifted from -99 to -147 ppm/°C.