Low‐temperature Sintering and Thermal Stability of Li2GeO3‐based Microwave Dielectric Ceramics with Low Permittivity

A low-permittivity dielectric ceramic Li2GeO3 was prepared by the solid-state reaction route. Single-phase Li2GeO3 crystallized in an orthorhombic structure. Dense ceramics with high relative density and homogeneous microstructure were obtained as sintered at 1000-1100 degrees C. The optimum microwave dielectric properties were achieved in the sample sintered at 1080 degrees C with a high relative density similar to 96%, a relative permittivity epsilon(r) similar to 6.36, a quality factor Qxf similar to 29000 GHz (at14.5 GHz), and a temperature coefficient of resonance frequency (f)similar to-72ppm/C-degrees. The sintering temperature of Li2GeO3 was successfully lowered via the appropriate addition of B2O3. Only 2 wt.% B2O3 addition contributed to a 21.2% decrease in sintering temperature to 850 degrees C without deteriorating the dielectric properties. The temperature dependence of the resonance frequency was successfully suppressed by the addition of TiO2 to form Li2TiO3 with a positive (f)value. These results demonstrate potential applications of Li2GeO3 in low-temperature cofiring ceramics technology.