Microwave dielectric properties of B2O3-doped ZnTiO3 ceramics made with sol–gel technique

Nano-sized B2O3-doped ZnTiO3 particles were successfully synthesized through sol–gel technique. The crystallization temperature of ZnTiO3 from sol–gel process was confirmed at 800 °C by the X-ray diffraction (XRD), thermo gravimetric (TG) and differential scanning calorimetry (DSC) analysis. The B2O3 content, the high molding pressure and the sintering temperature had great influence on microstructure and the dielectric properties of materials. According to scanning electron microscopy (SEM) analysis, when sintering reagent (B2O3) content was 1 wt.%, the grain growth of ZnTiO3 sintered at 900 °C was anisotropic, and the grain became regular disc structure with a diameter of 2 μm and thickness of 0.3 μm, which might be attributed to the selective growth of crystal grain in a preferential direction. As-prepared 1.0 wt.% B2O3-doped ZnTiO3 sintered at 900 °C for 4 h possessed excellent dielectric properties: Q × f = 49,000 GHz, ɛr = 8.87, τf = −32.35 ppm/°C. The nano-sized, uniform grains contributed to the high quality factor. The porous bulk ceramics contributed to the low dielectric constant.