Microwave dielectric properties of low-temperature-fired LiAlO2–Li2TiO3 composite ceramics with near-zero temperature coefficient

Abstract

A series of LiAlO2–Li2TiO3 ceramics with near-zero temperature coefficient of resonant frequency was obtained by using a solid-state method in this study. Li2O–B2O3–SiO2–CaO–Al2O3 (LBSCA) glass was used to lower the sintering temperature of the ceramics to approximately 900 °C. Scanning electron microscope images illustrated the dense microstructures of the LiAlO2–Li2TiO3 ceramics when amount of LBSCA glass content exceeded 1.0 wt%. X-ray diffraction analyses indicated that LiAlO2 and Li2TiO3 were presented as separate phases in the composites and no any secondary phase was observed in the sintered samples. High-performance microwave dielectric properties with permittivity of ∼ 15.4, Q × f value of ∼ 52,740 GHz and τf value of ∼ + 1.37 ppm/°C were observed in the LiAlO2–Li2TiO3 ceramic sample sintered at 900 °C with 1.5 wt% LBSCA glass. The ceramic also exhibited excellent chemical compatibility with Ag, which indicated that the fabricated material could be a good candidate for low-temperature co-fired ceramic applications.