Synthesis, sintering and microwave dielectric properties of Zn-doped Li3Mg4NbO8 ceramics

In this work, the effect of ionic substitution at the Mg-site in pure Li3Mg4NbO8 ceramics, including sintering characteristics and microwave properties, has been investigated for the first time. A novel Li3(Mg1−xZnx)4NbO8 ceramic has been successfully synthesized via the solid-phase reaction method by replacing Mg2+ with appropriate amounts of Zn2+. The relationship between crystal structure and properties has been established based on complex chemical bonding theory. There is a strong correlation between dielectric constant and ionicity, while the quality factor is related to the density and the lattice energy. The temperature coefficient of the resonance frequency and the dielectric constant after correction for porosity are closely related. Doping with appropriate amounts of Zn2+ can significantly improve the properties of pure Li3Mg4NbO8 ceramics. The Li3(Mg0.96Zn0.04)4NbO8 ceramic obtained at x = 0.04 has the following sintering properties at 1075 °C: εr = 15.0 ± 0.08, Q×f = 121,157 ± 1300 GHz, τf = −8.23 ± 0.11 ppm/°C, which combines characteristics of low dielectric constant, high quality factor, and temperature coefficient close to zero. Therefore, the resulting ceramic can be an ideal microwave dielectric material for the miniaturization and integration of microwave devices in 5 G.