Structural and magnetic properties of Copper substituted Bismuth Ferrite nanoparticles

Abstract

The influence of Cu²⁺ substitution on magnetic properties of nano particles of ferrite of basic composition Bi_1-xCu_xFeO_3-x/2 (0.0 ≤ x <1.0) synthesized by solid-state reaction method have been analyzed in this report. X-ray diffraction (XRD), Electron paramagnetic resonance (EPR) spectroscopy and Fourier transformation infrared (FTIR) spectroscopy techniques were used to investigate the structural and magnetic properties of the synthesized nanoparticles. XRD results confirm that all the samples are in single-phase with rhombic structure. The unit cell parameters “a” and “c” are calculated and found that these change with variation of composition. The average crystallite size of the synthesized nanoparticles is obtained through Scherner formula and is found to be 54 nm and it decreases with increase in the concentration of doping. EPR spectrum exhibits only one broad resonance with g about 2.56 suggesting the presence of oxygen vacancy and Fe³⁺in rhombic structure. EPR results indicate that the compound is in single phase only. The g value calculated for Fe(III) for all the samples is almost the same and is about 2.56. EPR results further confirming that metal ion is placed in rhombic crystal structure. It is found that the magnetic phase transition for pure BFO is due to spin-reorientation. Temperature dependence EPR signals like resonance field, g-factor, line-width, intensity, and asymmetric parameter are doping dependent. Temperature dependence magnetic measurements are strongly support the EPR results and indicate that there are two magnetic phases at low temperature and after 250 K only paramagnetic behaviour is present in the compound. FTIR spectrum indicates the presence of M-O bands along with OH vibrations.