Analysis of Raman, Mossbauer Spectra and Dielectric Behaviour of Sol-Gel Prepared Ni_1-xCo_xFe₂O₄ Spinel Ferrites

Abstract

Single-phase spinel ferrites with formula of Ni1-xCoxFe2O4 where x values vary from 0 to 1 with 0.25 steps were synthesized by sol-gel technique. Microstructure, cation distribution, valence state of iron, and dielectric properties are discussed. From the deconvoluted Raman spectra the positions of five Raman modes and intensity variation was calculated. Cationic arrangement in A and B sites was estimated from deconvoluted Raman peaks. The characteristic magnetic patterns of ferrites were given by room-temperature Mossbauer spectra. Parameters like isomer shift, hyperfine magnetic field, quadrupole shift were estimated for all ferrites after fitting Mossbauer spectra. From X-ray photoelectron spectroscopy analysis +3 ionic state for iron was found. Dielectric parameters were also studied for ferrites at room temperature. NiFe2O4 and Ni0.75Co0.25Fe2O4 had high values of dielectric permittivity, AC conductivity and loss tangent. The ferrite Ni0.5Co0.5Fe2O4 showed very less dielectric constant and conductivity values and dielectric loss resonance peak was around 1 kHz.

Effect of Zr, Sm and Gd Doped CoFe2O4 on Structural, Spectral and Magnetic Properties

“…All three materials also show a sharp peak around 1350 cm −1 , which is due to the O-H stretching vibration, indicating the presence of hydroxyl groups. 37 CoZr 0.05 Fe 1.95 O 4 has additional peaks between 600 and 900 cm −1 attributed to Zr-O stretching vibrations. The Fe-O peak Compared to Fe and Zr, the ionic radius of Sm 3+ and Gd 3+ ions is larger.…”

“…The highest intensity peak (311) reflection agrees with the theory that the angle has been generated through a face-centered cubic spinel structure. [34][35][36][37] To estimate the crystallite size, Scherrer's equation has been used.…”