Microwave dielectric properties of ultra-low loss Li2Mg4Zr0.95(Mg1/3Ta2/3)0.05O7 ceramics sintered at low temperature by LiF addition

Abstract

In this study, Li2Mg4Zr0.95(Mg1/3Ta2/3)0.05O7 (LMZT) ceramics were prepared via the conventional solid-state method. A cubic rock-salt structure with space group of Fm-3m was observed in all samples. Excellent microwave dielectric properties of εr = 12.68, Q × f = 190,403 GHz and τf = −20.64 ppm/°C were achieved for LMZT ceramic at 1500 °C. The variations in microwave dielectric properties were systematic investigated by polarizability, packing fraction and infrared spectrum. The complex dielectric loss was calculated from the fitting data of far infrared spectrum, which was in good agreement with the measured value. Moreover, the sintering characteristics, phase composition and microwave dielectric properties of LMZT-x wt.% LiF ceramics were researched. Dense microstructure could be gained at 1000 °C for 4 and 5 wt% LiF-doped LMZT ceramics due to liquid-phase sintering. The LMZT ceramics with 4 wt% LiF addition possessed excellent microwave dielectric properties: dielectric constant of 14.35, quality factor of 130,1030 GHz, temperature coefficient of resonant of −30.24 ppm/°C at 1000 °C.