Influence of 4ZnO–B ₂ O ₃ Addition on Dielectric Properties and Microstructures of Barium Strontium Titanate

This study investigates the effect of 4ZnO–B ₂ O ₃ on the sintering behavior, dielectric properties, and microstructures of Ba _0.6 Sr _0.4 TiO ₃ (BST) ceramics. These ceramics were sintered in air at temperatures ranging from 900°C to 1080°C. BST ceramics with 4ZnO–B ₂ O ₃ addition can be sintered to a theoretical density higher than 95% at 1050°C. A secondary phase (Ba ₂ ZnTi ₅ O ₁₃ ) is produced in the BST ceramics during 4ZnO–B ₂ O ₃ addition. Compositional analysis using TEM‐EDX of the BST ceramics with 3 wt% 4ZnO–B ₂ O ₃ revealed that the Zn ion is generally located at the triple points. This result indicates that BaO, TiO ₂ , 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–B ₂ O ₃ additives increased. In addition, the original Ba _0.6 Sr _0.4 TiO ₃ phase was shifted to the Ba _0.5 Sr _0.5 TiO ₃ phase by the addition of 3 wt% 4ZnO–B ₂ O ₃ at 1050°C. The Ba _0.6 Sr _0.4 TiO ₃ ceramic with 2 wt% 4ZnO–B ₂ O ₃ sintered at 1050°C in air for 2 h exhibited dielectric properties of ɛ _r =1883 and dissipation loss=0.36%. Moreover, BST with 1 wt% 4ZnO–B ₂ O ₃ addition sintered at 1080°C exhibits dielectric properties of ɛ _r =2330, dissipation loss=0.29%, and bulk density >95% of theoretical density.