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Dielectric property-microstructure relation in MgTiO3-CaTiO3 ceramics

Ergin Örek, Merve
A magnesium titanate - calcium titanate (MgTiO3-CaTiO3) dielectric ceramic with the mole percent composition of 95MgTiO3-5CaTiO3 (M0.95CT), was prepared from high purity powders of MgO, CaCO3, and TiO2 by conventional mixed-oxide route at various sintering temperatures ranging from 1200 to 1300 °C for 2, 4, and 6 h. The maximum densification and optimum dielectric properties were obtained for the M0.95CT ceramic sintered at 1250 °C for 4 h. The bulk density was 3.82 g/cm3 which corresponds to 97.5% of theoretical density. The dielectric constant and dielectric loss values were 20.6 and 0.0003 (1 kHz-40 MHz), respectively. The effects of small amounts (0.25, 0.50, 0.75, and 1.00 wt%) of Zn3B2O6, selected as liquid phase sintering aid, additions on the microstructural development, densification, and dielectric properties of M0.95CT ceramics were also investigated. The results revealed that incorporation of Zn3B2O6 caused abnormal grain growth. Densification and dielectric constant of 0.75 wt% Zn3B2O6 added M0.95CT ceramic decreased to 92% of theoretical density and 13.8, respectively but, dielectric loss increased to 0.0006. The low-temperature sintered microstructures of pure and Zn3B2O6 added M0.95CT ceramics were correlated with the dielectric properties.