Crystal structure and microwave dielectric properties of [(Mg0.6Zn0.4)0.95Co0.05]2TiO4-modified Ca0.6La0.8/3TiO3 cordierite ceramics with a near-zero temperature coefficient

The microstructure and dielectric properties of x[(Mg 0.6 Zn 0.4 ) 0.95 Co 0.05 ] 2 TiO 4 –(1 − x)Ca 0.6 La 0.8/3 TiO 3 (x = 0.9–0.96) ceramics prepared via conventional solid-state method were investigated using scanning electron microscopy and a network analyzer. Mixed phases of [(Mg 0.6 Zn 0.4 ) 0.95 Co 0.05 ] 2 TiO 4 and Ca 0.6 La 0.8/3 TiO 3 were detected using X-ray diffraction. The microwave dielectric properties are strongly correlated with the sintering temperature. Temperature coefficient of resonant frequency could be controlled by amount of Ca 0.6 La 0.8/3 TiO 3 and thus near-zero temperature coefficient value can be obtained. With x = 0.94 sintered at 1175 °C for 4 h, the proposed dielectric material, applicable to microwave devices, has the following dielectric properties: a dielectric constant ~ 18.1, a quality factor value of ~ 156,000 (at 9 GHz), and temperature coefficient of resonant frequency of 1.2 ppm/°C.