Abstract
The compositions, structure and dielectric properties of Bi 1.5+x/2 Zn 0.5 + x/6 Ti_1.5-1.5xNb 0.5+5x/6 O 7 (0.1 ≤ x ≤ 0.75, BZNT) ceramic in the Bi 2 O 3 -ZnO-Nb 2 O 5 - TiO 2 quaternary system were investigated. The structure of the samples exhibits a pure pyrochlore phase with x ≤ 0.3; a small amount of impurity with x = 0.5; a coexistence of cubic pyrochlore phase and monoclinic zirconolite phase with x = 0.75. Dielectric constant at 1 MHz decrease from 191 to 112 with the increase of x. Dielectric losses of all samples remain in the level of (1∼4) × 10−4. A typical dielectric relaxation behavior was also observed in all compositions, and the temperature of the permittivity peak increased linearly with the increase of x. Q value is within the range of 50 to 70 at resonate frequency of 2∼3 GHz.
Acknowledgments
This work is supported by the Ministry of Science and Technology of China through 973-project (No. 2002CB613302), the key project of Chinese Ministry of Education (No. 108055), Shanghai Pujiang Program and National Natural Science Foundation of China (No. 10874130).