The relationship between the micro-mechanism and macroscopic dielectric properties in Ba1−xBixTi1−x−yZn0.75xW0.25x+yO3+y systems

A novel lead-free, high dielectric constant, ultra-wide temperature stable dielectric ceramic Ba1−xBixTi1−x−yZn0.75xW0.25x+yO3+y (0.22≤x≤0.30, y=0.015) was synthesized by the traditional solid-state reaction method. The phase composition, electric and dielectric properties of the Ba1−xBixTi1−x−yZn0.75xW0.25x+yO3 ceramics were investigated. The P-V-L dielectric theory was introduced. And, the chemical bond energy was calculated to track the changes in micro-structure. The relationships between chemical bond energy and the macroscopic dielectric properties(εr, dielectric stability and dielectric loss) in Ba1−xBixTi1−x−yZn0.75xW0.25x+yO3+y ceramics were discussed systematically. Owing to the inhomogeneous micro-structure and the diffusion in phase transition, Ba1−xBixTi1−x−yZn0.75xW0.25x+yO3+y ceramics showed a stable permittivity (~800±15%) over a ultra-wide temperature range (−30 to 375 °C). Moreover, dielectric loss was less than 0.02 and the insulation resistance was over 1012 Ω cm. These features suggested that the Ba1−xBixTi1−x−yZn0.75xW0.25x+yO3+y ceramic could be considered as a promising candidate material for energy storage applications in harsh environment.