Structural evolution and dielectric properties of (1-x)Sr2SiO4-xBa0.5Sr0.5TiO3 microwave dielectric ceramics

Microwave dielectric ceramics of Sr 2 SiO 4 incorporated with different contents of Ba 0.5 Sr 0.5 TiO 3 were prepared using a solid-phase reaction. Their phase composition, micro-structure evolution and dielectric properties were investigated systematically. The results reveal that increasing the x content to 50 wt% leads to greater lattice distortion and defects formation caused by ion substitution within the composite ceramics, resulting in an increase in the dielectric permittivity while a degradation in the Q value. As the x content continues to increase, the enhanced connectivity and ferroelectric properties caused by Ba 0.5 Sr 0.5 TiO 3 within the composite ceramics trigger a sharp increase in the dielectric permittivity. However, the deterioration in Q value is suppressed by the composite effect, and its value gradually increases. At the same time, structural transformations occur within the composites, possessing relaxation properties. Optimal microwave dielectric performance is achieved at x  = 25 wt%, indicating balanced properties with ε r  = 26.41, Q = 1578 (4.658 GHz), and tanδ = 0.001581.