Multiferroic Fe³⁺ ion doped BaTiO₃ perovskite nanoceramics: Structural, optical, electrical and dielectric investigations

In the present investigation, nano crystalline Sr_0.5Ba_0.5Ti_1-xFe_xO₃ (x = 0.00, 0.15, 0.20) nanoparticles (BST) were synthesized by sol-gel auto combustion method. The effect of iron (Fe) doping on the structural, electric and dielectric and optical properties examined by the X-Ray diffraction (XRD), two probe and UV-vis techniques. XRD analysis shows that prepared samples are in a single phase with the tetragonal structure at room temperature. Structural parameters like average crystallite size (D) and lattice constant (a and c) were calculated from the XRD data. The surface morphology of the samples was studied by field emission scanning electron microscopy (FE-SEM) technique. It was found that the nanoparticles are cubic in shape for parent BST nanoparticle whereas Fe doped shows tetragonal shape. Energy dispersive spectrum (EDS) reveals that compositional elements are in stoichiometry proportion. The DC electrical resistivity measurements of the prepared samples were carried out in the temperature range of 300-850 K using a standard two-probe method. The electrical resistivity (?) decreases with temperature and Fe concentration. The frequency dependence of dielectric parameters such as dielectric constant (?) and loss tangent (tan L) was measured at room temperature in the frequency range of 30Hz to 1MHz. The dielectric parameters show strong compositional as well as frequency dependence. The higher values of dielectric parameters were found at lower frequencies. UV-visible absorption spectra showed that absorption edge shifted to higher wavelength with increasing Fe concentration while corresponding energy band gap of the prepared nanoceramics decreases with increasing Fe concentration.