Structure and dielectric characteristics of Ba1-xCaxTi1-xCaxO3-δ ceramics

The effect of Ca2+ substitution on the structure, dielectric, ferroelectric and optical properties of BaTiO3 processed via solid state route were investigated. X-ray diffraction analysis of the Ba1-xCaxTi1-xCaxO3-delta samples revealed the formation of single-phase perovskite structure for x <= 0.05 while secondary phase (BaCaTiO4) formed for x = 0.07. Raman spectroscopy results were in good agreement with the XRD data. Microstructural analysis revealed an increase in grain size with increase in Ca concentration. The Curie point (T-c) shifted to room temperature as x value increased. Energy density calculated from the P-E hysteresis loops showed an increase in energy density storage efficiency with Ca-concentration and was found to be 84% for x = 0.05 sample. The optical band gap of the samples varied from 2.84 to 3.14 eV with change in x which was associated to the phase transition and oxygen vacancies.