Microwave dielectric properties of (1 − x)(Mg0.4Zn0.6)2SiO4–xCaTiO3 composite ceramics

Phase formation, microstructure and microwave dielectric properties of (1 − x)(Mg0.4Zn0.6)2SiO4–xCaTiO3 (MZS-C) composite ceramics synthesized by using the conventional solid-state method were systematically investigated. Three phase structure was observed in all samples by using X-ray diffraction and the back scattering electron images. Mg2SiO4 can form a solid solution with Zn2SiO4, which improved sinterability of the MZS-C composite ceramics. As the CaTiO3 content was increased from 0.06 to 0.14, dielectric constant er and temperature coefficient of resonant frequency τf values of the MZS-C ceramics sintered at 1,180 °C for 4 h increased from 6.74 to 8.35 and −41.5 to −6.46 ppm/°C, respectively. Zero τf value can be obtained by properly adjusting the x value of the (1 − x)MZS–xC ceramics. With increasing content of CaTiO3, densification temperatures of the composite ceramics were decreased. The composite ceramic with x = 0.14 sintered at 1,180 °C for 4 h exhibited excellent microwave dielectric properties of er = 8.35, Q × f = 28,125 GHz and τf = −6.46 ppm/°C.