Influence of Ba substitution on the phase, microstructure, dielectric, and impedance properties of CaTiO3 ceramics

Ca[Formula: see text][Formula: see text]Ba[Formula: see text]TiO 3 ceramic powders, with [Formula: see text][Formula: see text]0 (CT), 0.2 (CBT1), 0.4 (CBT2), 0.6 (CBT3) and 0.8 (CBT4) (mole %) were prepared by the solid-state reaction method using ball milling. The samples were sintered at 1300[Formula: see text]C for 3 h in air atmosphere. X-ray diffraction (XRD) studies reveal the orthorhombic perovskite structure of pure CaTiO 3 and coexistence of both orthorhombic and tetragonal perovskite structures with the substitution of Ba content in CaTiO 3 . A biphasic structure is significant at [Formula: see text][Formula: see text] 0.4 (mole %) and [Formula: see text][Formula: see text] 0.6 (mole %) of Ba substitution in CaTiO 3 . The grain growth and microstructure of the sintered samples were examined by scanning electron microscopy (SEM). A reduction in grain size is observed from pure CaTiO 3 for the sample 0.6 mole % of Ba substitution in CaTiO 3 and then a significant increase in grain size is observed for CBT4. Dielectric properties of Ca[Formula: see text][Formula: see text]Ba[Formula: see text]TiO 3 ceramic powders over a frequency range of 1000 Hz–1 MHz were studied at room temperature. Among all the samples CBT2 (0.4 mole % of Ba) was found to obtain highest dielectric constant, minimum impedance and maximum AC conductivity, of 623, 2517 [Formula: see text] and 3.46 × 10[Formula: see text]S/m, respectively at 100 KHz. Further improvement in dielectric properties of the ceramic powders was studied over a frequency range of 1000 Hz–1 MHz with temperature increasing up to 400[Formula: see text]C. It was concluded that Ba-doped CaTiO 3 with 0.4 mole % was found to be the best sample among all others and hence suitable for MLCCs, Microwave resonators and tunable dielectric devices.