Influence of 4ZnO–B2O3 Addition on Dielectric Properties and Microstructures of Barium Strontium Titanate

This study investigates the effect of 4ZnO–B2O3 on the sintering behavior, dielectric properties, and microstructures of Ba0.6Sr0.4TiO3 (BST) ceramics. These ceramics were sintered in air at temperatures ranging from 900°C to 1080°C. BST ceramics with 4ZnO–B2O3 addition can be sintered to a theoretical density higher than 95% at 1050°C. A secondary phase (Ba2ZnTi5O13) is produced in the BST ceramics during 4ZnO–B2O3 addition. Compositional analysis using TEM-EDX of the BST ceramics with 3 wt% 4ZnO–B2O3 revealed that the Zn ion is generally located at the triple points. This result indicates that BaO, TiO2, and ZnO form a liquid phase that acts as a secondary phase at the lower sintering temperatures. The amount of secondary phase was observed to increase as the amount of 4ZnO–B2O3 additives increased. In addition, the original Ba0.6Sr0.4TiO3 phase was shifted to the Ba0.5Sr0.5TiO3 phase by the addition of 3 wt% 4ZnO–B2O3 at 1050°C. The Ba0.6Sr0.4TiO3 ceramic with 2 wt% 4ZnO–B2O3 sintered at 1050°C in air for 2 h exhibited dielectric properties of ɛr=1883 and dissipation loss=0.36%. Moreover, BST with 1 wt% 4ZnO–B2O3 addition sintered at 1080°C exhibits dielectric properties of ɛr=2330, dissipation loss=0.29%, and bulk density >95% of theoretical density.