A novel low-firing microwave dielectric ceramic Li2ZnGe3O8 with cubic spinel structure. Issue 2 (February 2017) - Xiang, Huaicheng
Abstract: A Li2 ZnGe3 O8 ceramic was investigated as a promising microwave dielectric material for low-temperature co-fired ceramics applications. Li2 ZnGe3 O8 ceramic was prepared via the conventional solid-state method. X-ray diffraction data shows that Li2 ZnGe3 O8 ceramic crystallized into a cubic spinel structure with a space group of P 41 32. Dense ceramic with a relative densities of 96.3% were obtained when sintered at 945 °C for 4 h and exhibited the optimum microwave properties with a relative permittivity ( εr ) of 10.3, a quality factor ( Q × f ) of 47, 400 GHz (at 13.3 GHz), and a temperature coefficient of resonance frequency ( τf ) of −63.9 ppm/°C. The large negative τf of Li2 ZnGe3 O8 ceramic could be compensated by rutile TiO2, and 0.9Li2 ZnGe3 O8 –0.1TiO2 0·1TiO2 ceramic sintered at 950 °C for 4 h exhibited improved microwave dielectric properties with a near-zero τf of −1.6 ppm/°C along with εr of 11.3 and a Q × f of 35, 800 GHz (11.6 GHz). Moreover, Li2 ZnGe3 O8 was found to be chemically compatible with silver electrode when sintered at 945 °C.