Magneto-electric/dielectric and fluorescence effects in multiferroic xBaTiO3–(1 − x)ZnFe2O4 nanostructures

Abstract

Multiferroic composites of xBaTiO₃–(1 − x)ZnFe₂O₄ (BTZF) [x = 0.25 (BTZF2575), 0.35 (BTZF3565), 0.45 (BTZF4555), 0.50 (BTZF5050) and 0.75 (BTZF7525)] nanostructure have been synthesized by a sol–gel method. Different types of nanostructural shapes and sizes have been obtained by the effect of ionic radii, surface energy and poly vinyl alcohol, which enhances the magneto-electric/dielectric interaction between BT/ZF phases. The crystalline phases of BTZF composite are confirmed by X-ray diffraction, and nanostructural dimensions and shape by transmission electron microscopy. The improvement in magnetization of BTZF is dependent upon the size and shape of the nanostructure, stoichiometric ratio and strength of occupation of cations at octahedral and tetrahedral sites. The chemical states of Fe in BTZF are analyzed by X-ray photoelectron spectroscopy. The ferroelectric property is explained by the nano size effect, 1D nanostructure shape, lattice distortion and epitaxial strain between two phases. The magnetoelectric coefficient is measured at room temperature under an applied dc magnetizing field and show different types of behavior in each sample. The magnetocapacitance is measured and explained on the basis of Maxwell–Wagner space charge and magnetoresistance, and relates to theoretical investigation, which proves that the enhancement not only depends on the size/shape of nanostructure but also the strain-induced phase transition where out-of-plane polarization appears in the composite. The photoemission of BTZF is observed by fluorescence spectroscopy.