Improved high Q value of 0.5LaAlO3-0.5SrTiO3 microwave dielectric ceramics at low sintering temperature

The dielectric properties and the microstructures of 0.5LaAlO3-0.5SrTiO3 ceramics with B2O3 additions (0.25 − 1 wt%) prepared with conventional solid-state route have been investigated. Doping with B2O3 (up to 0.5 wt%) can effectively promote the densification and the dielectric properties of 0.5LaAlO3-0.5SrTiO3 ceramics. It is found that LaAlO3-SrTiO3 ceramics can be sintered at 1400°C due to the liquid phase effect of B2O3 addition observed by Scanning Electronic Microscopy. The dielectric constant as well as the Q × f value decreases with increasing B2O3 content. At 1430°C, 0.5LaAlO3-0.5SrTiO3 ceramics with 0.25 wt% B2O3 addition possesses a dielectric constant (ε r) of 34.5, a Q × f value of 43,200 (at 7 GHz) and a temperature coefficient of resonant frequency (τf) of −10.7 ppm/°C.