Spontaneous, high temperature and spectroscopic characterization of K0.5Bi0.5TiO3-NaVO3 ceramic

Ferroelectric, optical and impedance properties of polycrystalline K0.5Bi0.5TiO3-NaVO3 (KBT-NV) ceramic prepared by solid state reaction technique has been investigated. Field Emission Scanning Electron Microscope (FESEM) study of the gold coated sintered pellet of the sample exhibits uniform distribution of small grains with well-defined grain boundaries. The Fourier Transform Infrared (FTIR) spectra show that the compound exhibits an appreciable change in its vibrational phonon modes of KBT on addition of NaVO3. The X-ray diffraction (XRD) reveals an orthorhombic structure where the crystallites preferentially grows along (6 2 0) face. Studies on nature of polarization, variation of dielectric constant, and tangent loss with temperature as well as frequency indicate the possible existence of ferroelectricity. The temperature variation of hysteresis loop confirms the ferroelectric nature in the studied compound. The sample is found to be photoluminescent in the wavelength range of 540-570 nm with a strong greenish-red emission which originates from defects. The optical band gap of the KBT-NV sample has been estimated from diffused reflectance and absorbance spectra to be 2.68 eV, which can be useful for photocatalytic application. (c) 2018 Elsevier B.V. All rights reserved.