Crystal structure and dielectric properties of La(Mg1−xZnx)1/2Ti1/2O3 ceramics at microwave frequencies

Ceramics in the system La(Mg1−xZnx)1/2Ti1/2O3 with B2O3 additions (1 wt.%) have been investigated by the conventional solid-state route. The XRD patterns of the sintered samples (0.3 ≤ x ≤ 1.0) revealed single phase formation with a structure. The unit cell volume slightly increased with increasing Zn content (x). La(Mg1−xZnx)1/2Ti1/2O3 were found to form perovskite solid solutions in the whole compositional range. The maximum values of the dielectric constant and the quality factor multiples resonant frequency (Q × f) can be obtained when the La(Mg0.7Zn0.3)1/2Ti1/2O3 with 0.5 wt.% B2O3 additive were sintered at 1475 °C for 4 h. The temperature coefficient of resonant frequency τf (−63 ppm/°C) was measured for x = 0.7.

Research highlightsThe dielectric properties of B2O3-doped La(Mg1−xZnx)1/2Ti1/2O3 ceramics were investigated. La(Mg1−xZnx)1/2Ti1/2O3 ceramics exhibited perovskite structure. With 1 wt.% B2O3 addition, a dielectric constant of 28.97, a Q × f value of 74,000 (GHz) and a τf value of −62.5 ppm/°C were obtained for La(Mg1−xZnx)1/2Ti1/2O3 (x = 0.3) ceramics at 1475 °C for 4 h. The decrease in Q × f value at higher sintering temperature and more Zn2+ content was owing to that the grain boundary phases were pronounced product and ZnO evaporation. Therefore, the B2O3-doped La(Mg1−xZnx)1/2Ti1/2O3 ceramic is suitable for applications in microwave dielectric resonators and microwave device because of its excellent microwave dielectric properties.