Effects of adding B2O3 on microwave dielectric properties of 0.9625MgTiO3‐0.0375(Ca0.5Sr0.5)TiO3 composite ceramics

Abstract

AbstractA series of 0.9625MgTiO3‐0.0375(Ca0.5Sr0.5)TiO3 composite ceramics added with different amounts of B2O3 (1‐5 wt%) were prepared via the solid state sintering method using the pre‐synthesized raw MgTiO3 and (Ca0.5Sr0.5)TiO3 powders by molten‐salt reaction. The sintering temperature of 0.9625MgTiO3‐0.0375(Ca0.5Sr0.5)TiO3 composite ceramics can be reduced from 1275°C to 1175°C due to the liquid phase sintering effect of B2O3. When the adding amount of B2O3 was more than 2 wt%, a new phase MgTi2O5 could be detected by X‐ray diffraction, which would substantially degrade the dielectric properties of the obtained ceramics. Resultantly, the quality factor (Q·f) and dielectric constant (εr) of the samples increase first and decrease later with increasing addition amount of B2O3. In addition, the temperature coefficient of resonant frequency (τf) progressively increases with increasing content of B2O3. By sintering at 1175°C for 4 hours, the obtained 0.9625MgTiO3‐0.0375Ca0.5Sr0.5TiO3 composite ceramics with 2 wt% B2O3 possess the optimal microwave dielectric properties of εr = 18.9, Q·f = 57 000 GHz and τf = −1.2 ppm/°C.