Study of the microstructure and the optical, electrical, and magnetic feature of the Dy2Bi2Fe4O12 ferromagnetic semiconductor

Abstract

With the aim to produce a material with magnetic and semiconductor properties, a lanthanide bismuth-ferrite type material is proposed in this work. Polycrystalline samples of Dy2Bi2Fe4O12 were produced following the standard solid-state reaction method. Structural characterization through the X-ray diffraction technique evidences that the synthesized ceramic crystallizes in a perovskite-like orthorhombic structure, belonging to the Pnma (#62) space group. Scanning electron microscopy images revealed the granular nature of the samples with mean grain sizes of nanometric order. X-ray energy dispersion spectra allowed establishing that in the samples there are no elements different from those expected in the stoichiometric proportions suggested by the chemical formula of the compound. Studies of electrical behavior were carried out using I–V curves and electrical permittivity as a function of frequency and temperature, which show the diode varistor feature of this material with a marked Maxwell–Wagner-type trend. The semiconductor band gap was determined from the analysis of diffuse reflectance spectra that reveal Eg = 1.88 eV. Temperature-dependent magnetization curves for applied fields of 1.0, 5.0 and 10 kOe showed the behavior expected for ferromagnetic type materials, with strong evidence of magnetic frustration causing irreversibility in curves obtained from Zero Field Cooling and Field Cooled measurement procedures. The magnetization hysteresis curves at temperatures of 50, 200 and 300 K exhibit a ferromagnetic response with evidence of superparamagnetic effects due to the significant presence of nano-sized ferromagnetic grains. Based on the obtained results, it can be affirmed that the material behaves like a soft ferrimagnetic semiconductor with low coercive field (between 500 Oe and 700 Oe) and remnant magnetization (between 2.15 × 10−4 emu/g and 3.25 × 10−4 emu/g) that would have eventual technological implications in the spintronic industry.

Keywords

• Crystal structure
• Ferromagnetic perovskite-like material
• Optical band gap
• Electric feature
• Semiconductor character