LiYGeO4: Novel low-permittivity microwave dielectric ceramics with intrinsic low sintering temperature

Using the solid-state reaction route, a new low-firing microwave dielectric ceramic LiYGeO4 was prepared, and the phase evolution, thermal stability, and dielectric properties were characterized. A single orthorhombic phase LiYGeO4 formed in the sintering temperature range of 920-960 °C decomposed into Y2GeO5, GeO2, and Li2O when the sintering temperature exceeded 960 °C. LiYGeO4 densified at 940 °C/6 h possessed a relative permittivity 9.41, a quality factor 18,860 GHz (at 12.8 GHz), and a temperature coefficient of resonant frequency −27.7 ppm/°C. The negative τf value was compensated by compositing with CaTiO3, and 0.97LiYGeO4-0.03CaTiO3 ceramic exhibited a near-zero τf of −1.37 ppm/°C along with a permittivity of 9.83 and a quality factor of 12,940 GHz (at 13.2 GHz). All merits make LiYGeO4 a promising candidate for high-frequency communication application, and low-temperature co-fired ceramics.