Synthesis conditions induced disorder and its role in affecting structural, dielectric, piezoelectric, optical behavior and enhancing energy storage efficiency in (Ba1-xCax)TiO3 ceramics

摘要

? 2022 Elsevier Ltd and Techna Group S.r.l.We examined the effect of Ca2+ substitution on the structural, dielectric, ferroelectric, piezoelectric, and optical properties of Barium Titanate (BT) prepared via the solid-state reaction route assisted with a heating cycle. X-ray diffraction (XRD) patterns confirmed the formation of single-phase perovskite structures for Ba1-xCaxTiO3, 0 ≤ x ≤ 0.08. Raman spectroscopy of the Ca2+ doped BT was in good agreement with the XRD data. Structural analysis revealed an increase in average grain size with the increase in Ca2+ concentration in BT except for BCT-5 (x = 0.05) whose average grain size decreased. The Curie temperature shifted towards a higher temperature with the increase in Ca2+ concentration in BT, which is consistent with the literature when Ca2+ goes into the Ba2+ site. For BCT-5, the decrease in average grain size and the increase in diffuseness parameter to 1.51 confirmed partial substitution of Ca2+ at Ti4+-site, generating oxygen vacancies that inhibited grain growth during the synthesis procedure. The recoverable energy density calculated from the PE hysteresis loop showed maximum value for BCT-3 = 224.3 mJ/cm3 with a storage efficiency of 85. The energy storage efficiency was greater than 80 for all the compositions, making them suitable for high energy density capacitors. The piezoelectric charge coefficient increased linearly with Ca2+ concentration except for BCT-5, due to partial substitution of Ca2+ at the Ti4+ site. The indirect optical bandgap varied from 1.97 eV to 2.24 eV with Ca2+ concentration associated with the combined effect of lattice disorder and defects, which can have applications in optoelectronics. Partial substitution of Ca2+ at the Ti4+ site decreased the optical bandgap of BCT-5.