Chemical bond characteristics and microwave dielectric properties of high-Q × f Li3+xMgNbO5Fx (0 ≤ x ≤ 1.25) ceramics for LTCC applications

A novel series of oxyfluoride rock salt-structured Li3+xMgNbO5Fx (0 ≤ x ≤ 1.25) ceramic specimens were prepared via a solid-state reaction route. The phase composition, microstructures, and microwave dielectric properties of the samples were investigated. The chemical bond theory was employed to reveal the composition dependence of the microwave dielectric properties of the Li3+xMgNbO5Fx samples. The optimal microwave dielectric properties of εr = 16.1, Q × f = 79200 GHz, τf=-40.8 ppm/°C were obtained in the specimen with x = 0.75 when sintered at 900℃. Additionally, the Li3.75MgNbO5F0.75 ceramics showed excellent chemical compatibility with Ag electrodes, which suggests that the present samples are promising candidate materials for low-temperature co-fired ceramic (LTCC) applications.