Influence of glass additives on the microwave dielectric properties of Ca5Nb2TiO12 ceramics

Investigation was made to correlate the effect of composition and concentration of glass content on the sintering temperature and microwave dielectric properties of polycrystalline Ca5Nb2TiO12 ceramics. Glass systems, such as B2O3, SiO2, B2O3-SiO2, ZnO-B2O3, Al2O3-SiO2, Al2O3-B2O3-SiO2, BaO-B2O3-SiO2, MgO-B2O3-SiO2, ZnO-B2O3-SiO2, PbO-B2O3-SiO2, and 2MgO-Al2O3-5SiO2 were added to calcined Ca5Nb2TiO12 powder in different weight percentages. The structure and microstructure of the sintered ceramics were studied using powder X-ray diffraction and scanning electron microscopic methods. The specimens were characterized in the microwave frequency range (3-6 GHz). The study revealed that alumina and silica based glasses were more effective in improving the dielectric properties of Ca5Nb2TiO12 ceramics, whereas borate glasses are more suited for lowering the sintering temperature.