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

Abstract The effects of B 2 O 3 addition on the microwave dielectric properties and the microstructures of (1− x )LaAlO 3 – x SrTiO 3 ceramics prepared by conventional solid-state routes have been investigated. Doping with 0.25 wt.% B 2 O 3 can effectively promote the densification and the microwave dielectric properties of (1− x )LaAlO 3 – x SrTiO 3 ceramics. It is found that LaAlO 3 –SrTiO 3 ceramics can be sintered at 1400°C due to the liquid phase effect of a B 2 O 3 addition observed by scanning electronic microscopy (SEM). The dielectric constant as well as the Q × f value decreases with increasing B 2 O 3 content. At 1460°C, 0.46LaAlO 3 –0.54SrTiO 3 ceramics with 0.25 wt.% B 2 O 3 addition possesses a dielectric constant ( e r ) of 35, a Q × f value of 38,000 (at 7 GHz) and a temperature coefficients of resonant frequency ( τ f ) of −1 ppm/°C.