Dielectric tunable properties of Ba_0.5Sr_0.5TiO₃–Li₂Mg₃TiO₆–Mg₂TiO₄ composite ceramics

50Ba_0.5Sr_0.5TiO₃–(50 − x)Li₂Mg₃TiO₆–xMg₂TiO₄ ternary ferroelectric-dielectric composite ceramics were prepared by the conventional solid-phase reaction method. The effect of Mg₂TiO₄ content on the structural characteristics and dielectric tunable properties of composite ceramics were researched. X-ray diffraction (XRD) analysis showed that Ba_0.5Sr_0.5TiO₃, Li₂Mg₃TiO₆ and Mg₂TiO₄ phases existed in the composite ceramics. The composite ceramics exhibit a broadened dielectric permittivity plateau region. Increasing the content of Mg₂TiO₄ led to an increase in dielectric permittivity and tunability of 50Ba_0.5Sr_0.5TiO₃–(50 − x)Li₂Mg₃TiO₆–xMg₂TiO₄ composite: the content of Mg₂TiO₄ increased from 5 to 40 wt%, the dielectric permittivity increased from 183 to 329, and the tunability under 3 kV/mm increased from 7 to 17.6%. The dielectric properties of Ba_0.5Sr_0.5TiO₃–Li₂Mg₃TiO₆–Mg₂TiO₄ are comparable to those of the corresponding Ba_0.5Sr_0.5TiO₃–Mg₂TiO₄ system, and the sintering temperature was reduced by 140 °C. The Ba_0.5Sr_0.5TiO₃–Li₂Mg₃TiO₆–Mg₂TiO₄ system composite ceramics are promising candidate materials for tunable microwave applications.