Microstructure and Microwave Dielectric Properties of TiO2‐Doped Zn2SiO4 Ceramics Synthesized Through the Sol–Gel Process

Abstract

(1−x)Zn2SiO4–xTiO2 (x=0, 5, 8, 11, and 15 wt%) ceramics have been successfully prepared through a sol–gel process. The thermal gravimetry‐differential thermal analysis and X‐ray diffraction analysis showed that the addition of TiO2 can lower the nucleation temperature of Zn2SiO4 and enhance the sinterability of the powders synthesized. Dense ceramics with a pure phase could be achieved at a lower temperature. The pure Zn2SiO4 ceramics sintered at 1325°C exhibited microwave dielectric properties: a dielectric constant (ɛr) of 6.6, a quality factor Q×f of 198 400 GHz, and a temperature coefficient of resonant frequency (τf) of −41.6 ppm/°C. The τf value can be adjusted to near zero by adding an appropriate amount of TiO2. The Zn2SiO4 ceramics containing 11 wt% of TiO2 sintered at 1200°C showed excellent microwave dielectric properties: an ɛr value of 9.1, a Q×f value of 150 800 GHz, and a τf value of −1.0 ppm/°C. Our results show that the sol–gel process can achieve pure phase as well as ultrafine powders, which is beneficial to optimize the performance of Zn2SiO4 ceramics. Zn2SiO4 ceramics containing 11 wt% of TiO2 are a promising candidate for microwave and millimeter‐wave applications.