Low-Temperature Sintering and Microwave Dielectric Properties of CuxZn1-xTi0.2Zr0.8Nb2O8 Ceramics with the Aid of LiF

M2+N4+Nb2O8-type ceramics (where M = Mg, Ca, Mn, Co, Ni, Zn and N = Ti, Zr) are essential for satellite communication and mobile base stations due to their medium relative permittivity (epsilon r) and high quality factor (Q x f). Although ZnTi0.2Zr0.8Nb2O8 ceramic exhibits impressive microwave dielectric properties, including an epsilon r of 29.75, a Q x f of 107,303 GHz, and a tau f of -24.41 ppm/degrees C, its sintering temperature of 1150 degrees C remains a significant barrier for integration into low-temperature co-fired ceramic (LTCC) technologies. To overcome this limitation, a strategy involving the partial substitution of Zn2+ with Cu2+ and the addition of LiF as a sintering aid was devised for ZnTi0.2Zr0.8Nb2O8. The dual impact of Cu2+ partial substitution and LiF as a sintering enhancer facilitated the successful sintering of Cu0.3Zn0.7Ti0.2Zr0.8Nb2O8 ceramics at a reduced temperature of 950 degrees C using the conventional solid-state reaction method. These ceramics exhibited excellent microwave dielectric properties. Notably, Cu0.3Zn0.7Ti0.2Zr0.8Nb2O8 ceramic with 40 mol% LiF addition demonstrated optimal microwave dielectric properties without any reaction with a silver electrode at a sintering temperature of 950 degrees C, yielding epsilon r = 32, Q x f = 45,543 GHz, and tau f = -43.5 ppm/degrees C.