Effect of Sr doping on phase structure, microstructure, and dielectric properties of Ba2TiSi2O8 ceramics

Ba 2 TiSi 2 O 8 ceramics exhibit excellent thermal, electrical, and optical properties, offering great potential for functional applications. However, the dielectric properties of Ba 2 TiSi 2 O 8 ceramics have not been systematically investigated. This study explores the structural and dielectric evolution of Sr-doped Ba 2 TiSi 2 O 8 ceramics (0 ≤ x ≤ 1.6), with particular attention to phase composition, microstructure, and vibrational behavior. All compositions retained the tetragonal P4bm structure, while a gradual lattice contraction was observed with increasing Sr 2+ content. This structural evolution is further supported by Raman spectroscopy, which revealed systematic blue shifts in the TiO 5 and Si 2 O 7 vibrational modes, indicating enhanced bond strength and increased lattice rigidity. These structural modifications promoted densification and microstructural uniformity. At x = 0.4, the ceramic exhibited high relative density (> 97.8%), uniform grains, and phase purity, resulting in superior dielectric performance ( \({\varepsilon }_{r}{\prime}\)  = 12.53, \(Q\times f\) = 2120 GHz, \({\tau }_{f}\) = − 23.63 ppm/°C). In contrast, excessive Sr 2+ content (x ≥ 0.8) induced abnormal grain growth and the emergence of secondary SrTiO 3 phases, accompanied by increased dielectric loss. These findings elucidate the delicate balance between lattice modification and dielectric response in Sr-doped Ba 2 TiSi 2 O 8 ceramics, offering valuable insight into the structural design of silicate-based microwave dielectric materials.