Novel low-εr and lightweight LiBO2 microwave dielectric ceramics with good chemical compatibility with silver

High-speed signal propagation systems require dielectric ceramics with low relative permittivity (ε r ) and a high-quality factor ( Qxf ). In this paper, a novel low-permittivity borate ceramic (LiBO 2 ) was synthesized using a conventional solid-state reaction method. Based on the X-ray diffraction and Rietveld refinement , the LiBO 2 crystallized into a monoclinic structure with a space group of P21/c. Dense and single-phase ceramic was obtained at 640 °C with comprehensive microwave dielectric properties : a low relative permittivity ( ε r ) of 5.3, a moderate quality factor ( Q × f ) of 18,200 GHz at 16.3 GHz, and a temperature coefficient of resonant frequency (τ f ) of − 66.2 ppm/°C. Good chemical compatibility with Ag electrode and thermal expansion coefficient of 25.4 ppm/°C was achieved demonstrating the potential applications as dielectric resonances in wireless communications and substrates in low-temperature cofired ceramics.