Synthesis of (Zn, Mg)TiO3–TiO2 composite ceramics for multilayer ceramic capacitors

(Zn0.8Mg0.2)TiO3–xTiO2 composite ceramics has been prepared via the solid-phase synthesis method. TiO2 was employed to tone temperature coefficient of resonant frequency (τf) and stabilize hexagonal (Zn, Mg)TiO3 phase. 3ZnO–B2O3 was effective to promote sintering. The movement of grain boundary was obvious because of the liquid phase sintering. The scanning electron microscope (SEM) photographs and energy dispersive spectrometer (EDS) patterns showed that segregation and precipitation of dissociative (Zn, Mg)TiO3 grains occurred at grain boundary during sintering. SnO2 was used as inhibitor to prevent the grain boundary from moving. The dielectric behaviors of specimen strongly depended on structural transition and microstructure. We found that 1.0 wt.% 3ZnO–B2O3 doped (Zn, Mg)TiO3–0.25TiO2 ceramics with 0.1 wt.% SnO2 additive displayed excellent dielectric properties (at 1000 °C): ɛr = 27.7, Q × f = 65,490 GHz (at 6.07 GHz) and τf = −8.88 ppm °C−1. The above-mentioned material was applied successfully to make multilayer ceramic capacitors (MLCCs), which exhibited an excellent electrical property. The self-resonance frequency (SRF) and equivalent series resistance (ESR) of capacitor decreased with capacitance increasing, and the quality factor (Q) of capacitor reduced as frequency or capacity increased.