Microstructure and microwave dielectric properties of (Zn1−x Mg x )2SiO4 ceramics

(ZnMg)2SiO4 powders was prepared by the sol-gel process, and the microstructure and dielectric properties of (Zn1−xMgx)2SiO4 microwave materials were investigated systematically. TG-DSC and XRD analyzes for gels indicate that the (ZnMg)2SiO4 with pure willemite phase could be obtained at low temperature of 850°C. Further, XRD illustrates that just small amounts of Mg can be incorporated into Zn2SiO4 lattice, and the solid solution limit of Mg in Zn2SiO4 is about x = 0·1. By appropriate Mg substitution for Zn, the sintering range is widened and the sintering temperature of Zn2SiO4 ceramics can be lowered effectively. SEM shows that Mg-substitution for Zn can promote the grain growth of Zn2SiO4. Moreover, the microwave dielectric properties strongly depended on the substitution content of Mg and sintering temperatures. (Zn0·8Mg0·2)2SiO4 dielectrics sintered at 1170°C show the condense microstructure with small uniform grains and best microwave properties: ɛ r = 6·3, Q × f = 189800 GHz and τ f = −63 ppm/°C.