Sintering Behaviors, Microstructure, and Microwave Dielectric Properties of CaTiO ₃–LaAlO ₃ Ceramics Using CuO/B ₂O ₃ Additions

Abstract

The effect of CuO/B ₂O ₃ additions on the sintering behaviors, microstructures, and microwave dielectric properties of 0.95LaAlO ₃–0.05CaTiO ₃ ceramics is investigated. It is found that the sintering temperatures are lowered efficiently from 1600 °C to 1350 °C, as 1 wt % CuO, 1 wt % B ₂O ₃, and 0.5 wt % CuO +0.5 wt % B ₂O ₃ are used as the sintering aids due to the appearance of the liquid phase sintering. The microwave dielectric properties of 0.95LaAlO ₃–0.05CaTiO ₃ ceramics with the sintering aid additions are strongly related to the densification and the microstructure of the sintered ceramics. At the sintering temperature of 1300 °C, the 0.95LaAlO ₃–0.05CaTiO ₃ ceramic with 0.5 wt % CuO + 0.5 wt % B ₂O ₃ addition shows the best dielectric properties, including a dielectric constant (ε _r) of 21, approximate quality factor (Q × f) of 22,500 GHz, and a temperature coefficient of the resonant frequency ( τ _f ) of −3 ppm/°C.