Glass-free low-temperature sintering and microwave dielectric properties of CaWO4–Li2WO4 ceramics

Abstract The microwave dielectric properties of (1− x ) CaWO 4 − x Li 2 WO 4 ceramics prepared by the solid state reaction were investigated as a function of Li 2 WO 4 content (0≤ x ≤0.14). Due to the addition of Li 2 WO 4 phase, the sintering temperature was reduced from 1150 °C to below the LTCC temperature limits. For the ceramics sintered at 900 °C and 950 °C, with the increase of x , the Q×f values first increased and then decreased. The density and permittivity presented the same behaviour as the Q×f values. At x =0.1, the (1− x )CaWO 4 − x Li 2 WO 4 ceramics sintered at 900 °C/2 h presented excellent microwave dielectric properties: e r =9.002, Q × f =11.76×10 4 GHz and τ f =−55 ppm/°C. The ceramic was a chemically compatible with silver, which makes it a very promising candidate for LTCC application.