Investigation on Multiferroic Behavior of Brownmillerite Composite by Thermal and Magnetic Field Perturbation

Abstract

Our investigation on the auto combustion sol-gel synthesized (1 − x)KBiF e2O5 − (x)NiF e2O4 composite, where 0 ≤ x ≤ 1, has been performed through the tempera-ture, magnetic field, and frequency-dependent scientific methods. Rietveld refinement analysis with a proper χ2 value confirms the purity, phase formation, and lattice pa-rameters. The surface morphology shows a drastic change in grain size from in x=0.1 (1.48 ± 0.05 µm) to x=0.2 (0.77 ± 0.03 µm). The progressive addition of NFO ran-domizes the grain size and produces slight variations. In the x=0.2 composite, the 113% improved dielectric permittivity is (17.46×104) saw in composite. The 4 times enhanced MR (5.04±0.09 emu/g); however, the trivial variation in the HC (15%) of 182±3 Oe in x=0.4. The magnetic anisotropy of NFO is reflected in the LAS fitting, yielding a value of 5.52×104 erg/cm3 for the x=0.4 composite. Diffuse reflectance spectroscopy (DRS) and the Kubelka-Munk (KM) method figure out the direct band gap (n=2) of 1.74 eV for x=0.4 composite, suitable for photovoltaic applications. A maximum of 2.01% magnetodielectric (MD) coupling at 10 kHz is seen for the x=0.1 composite. Investigation suggests that a composite with high dielectric and moderate magnetization properties is suitable for low-magnetic-field-controlled data storage, sensor, and spintronic device applications.