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

Abstract

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-δ 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 (Tc) 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.