Effect of Zn2+ doping Li2Mg3Ti0.91(Al0.5Nb0.5)0.09O6 on structures and microwave dielectric properties

Li2Mg3Ti0.91(Al0.5Nb0.5)0.09O6-based microwave dielectric ceramics with high dielectric constant, quality-factor and temperature stability were prepared by conventional solid-state reaction method. Influence of Zn2+ dopant on structures and microwave dielectric properties of Li2Mg3Ti0.91(Al0.5Nb0.5)0.09O6 ceramics were investigated by X-ray diffraction and Raman spectroscopy. The X-ray diffraction results showed that no new phase was produced with the zinc addition before y = 0.08, above that some ZnTiO3 peaks with very low intensity appear in the low-angle region of the diffraction pattern. The results of the scanning electronic microscope confirmed that Zn2+ doping helped grains growth, reduced grain boundaries and made grains distribution uniform. All of these improvements have led to great dielectric constant (εr), superior quality factor (Q×f) and outstanding temperature coefficient of resonance frequency (τf). A microwave dielectric ceramic based on Li2Mg3Ti0.91(Al0.5Nb0.5)0.09O6 with optimum Zn2+ content sintered at optimum temperature, exhibiting better comprehensive dielectric properties: εr = 14.51, Q×f = 158,120 GHz, τf = −13.0 ppm/°C.