A-Site Substituted BaTiO3: Analysis of Structural, Optical, Ferroelectric and Dielectric Nature

Abstract

The well-known ferroelectric and dielectric materials based on barium titanate (BaTiO3) with the compositional formula Ba[Formula: see text]AEMxTiO3 [[Formula: see text] and AEM (alkaline earth metal) [Formula: see text] Ca and Sr] denoted as BTO, BCTO and BSTO are reported in this work. The solid-state reaction method was used to synthesize these titanates. The as-synthesized samples were characterized for structural elucidation via X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Raman inelastic scattering, energy dispersive analysis of X-rays (EDAX) and field emission scanning electron microscopy (FESEM). In addition to this, the samples were studied for optical bandgap, dielectric constant, dielectric loss, ac conductivity and polarization ([Formula: see text]–[Formula: see text]) studies. The XRD data analysis revealed that all the samples have acquired a tetragonal structure (P4mm) and are single phased. The Rietveld refinement of Ba[Formula: see text]Ca[Formula: see text]TiO3 confirms XRD results. In FTIR spectra, the absorption modes appearing at about 400[Formula: see text]cm[Formula: see text] and 500[Formula: see text]cm[Formula: see text] are attributes of the vibration of Ti–O bonds and Ba–O bonds, confirming the formation of desired samples. The appearance of the Raman mode of vibration at about 310[Formula: see text]cm[Formula: see text] is an indication of the tetragonal phase. FESEM micrographs of Ba[Formula: see text]Ca[Formula: see text]TiO3 reveal grain growth in the range of about 1[Formula: see text][Formula: see text]m and its EDAX spectrum confirms the composition of the sample. The optical bandgap was found to be 3.35[Formula: see text]eV, 3.1[Formula: see text]eV and 2.65[Formula: see text]eV for pristine, Ca[Formula: see text]- and Sr[Formula: see text]-doped BaTiO3, respectively. Frequency-dependent dielectric studies infer the samples to be extremely good dielectrics in nature with very low loss values. Polarization against a field at 1000[Formula: see text]V witnesses the samples to exhibit low polarization effects with lossy character. The dielectric and [Formula: see text]–[Formula: see text] behavior of Ba[Formula: see text]Sr[Formula: see text]TiO3 was found exceptional among all the reported titanates.