Effect of CuO additive on sintering and microwave dielectric behavior of LaAlO3 ceramics

The dielectric properties and the microstructures of LaAlO3 ceramics with CuO additions (0.25–1 wt%) have been investigated. The sintered LaAlO3 ceramics are characterized by X-ray diffraction spectra and scanning electron microscopy (SEM). The ceramic samples show that a dielectric constant (ϵr) of 19–22 and a Q × f value of 5000–48,000(at 9.7 GHz) can be obtained at low sintering temperatures of 1370–1460°C. The temperature coefficient of resonant frequency varies from −50 to −80 ppm/°C. At the level of 0.5 wt% and 1 wt% CuO additions, low Q × f value of the LaAlO3 ceramics is owing to the formation of the second phase LaAl11O18. With CuO addition, an 100–200°C reduction in sintering temperature can be achieved for the LaAlO3 ceramics.