Dielectric properties of B2O3-doped (1 − x)LaAlO3–xSrTiO3 ceramic system at microwave frequency

The effects of B2O3 addition on the microwave dielectric properties and the microstructures of (1−x)LaAlO3–xSrTiO3 ceramics prepared by conventional solid-state routes have been investigated. Doping with 0.25 wt.% B2O3 can effectively promote the densification and the microwave dielectric properties of (1−x)LaAlO3–xSrTiO3 ceramics. It is found that LaAlO3–SrTiO3 ceramics can be sintered at 1400°C due to the liquid phase effect of a B2O3 addition observed by scanning electronic microscopy (SEM). The dielectric constant as well as the Q×f value decreases with increasing B2O3 content. At 1460°C, 0.46LaAlO3–0.54SrTiO3 ceramics with 0.25 wt.% B2O3 addition possesses a dielectric constant (εr) of 35, a Q×f value of 38,000 (at 7 GHz) and a temperature coefficients of resonant frequency (τf) of −1 ppm/°C.