Ali A. Ati

Cu2+ and Al3+ co-substituted cobalt ferrite: structural analysis, morphology and magnetic properties

Cu–Al substituted Co ferrite nanopowders, Co1−xCuxFe2−xAl xO4 (0.0 ≤ x ≤ 0.8) were synthesized by the co-precipitation method. The effect of Cu–Al substitution on the structural and magnetic properties have been investigated. X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM) are used for studying the effect of variation in the Cu–Al substitution and its impact on particle size, magnetic properties such as Ms and Hc. Cu–Al substitution occurs and produce a secondary phase, α-Fe 2O3. The crystallite size of the powder calcined at 800 ∘C was in the range of 19–26 nm. The lattice parameter decreases with increasing Cu–Al content. The nanostructural features were examined by FESEM images. Infrared absorption (IR) spectra shows two vibrational bands; at around 600 (v1) and 400 cm −1 (v2). They are attributed to the tetrahedral and octahedral group complexes of the spinel lattice, respectively. It was found that the physical and magnetic properties have changed with Cu–Al contents. The saturation magnetization decreases with the increase in Cu–Al substitution. The reduction of coercive force, saturation magnetization and magnetic moments are may be due to dilution of the magnetic interaction.

Effects of Mg substitution on the structural and magnetic properties of Co0.5Ni0.5-xMgxFe2O4 nanoparticle ferrites

In this study, nanocrystalline Co-Ni-Mg ferrite powders with composition Co0.5Ni0.5-xMgxFe2O4 are successfully synthesized by the co-precipitation method. A systematic investigation on the structural, morphological and magnetic properties of un-doped and Mg-doped Co-Ni ferrite nanoparticles is carried out. The prepared samples are characterized using x-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and vibrating sample magnetometry (VSM). The XRD analyses of the synthesized samples confirm the formation of single-phase cubic spinel structures with crystallite sizes in a range of similar to 32 nm to similar to 36 nm. The lattice constant increases with increasing Mg content. FESEM images show that the synthesized samples are homogeneous with a uniformly distributed grain. The results of IR spectroscopy analysis indicate the formation of functional groups of spinel ferrite in the co-precipitation process. By increasing Mg2+ substitution, room temperature magnetic measurement shows that maximum magnetization and coercivity increase from similar to 57.35 emu/g to similar to 61.49 emu/g and similar to 603.26 Oe to similar to 684.11 Oe (1 Oe = 79.5775 A.m(-1)), respectively. The higher values of magnetization M-s and M-r suggest that the optimum composition is Co0.5Ni0.4Mg0.1Fe2O4 that can be applied to high-density recording media and microwave devices.

The Effect of Sintering Temperature on the Structural and Magnetic Properties of Ni-Mg Substituted CoFe2O4 Nanoparticles

This study evaluates the structural and magnetic properties of Ni-Mg substituted Cobalt ferrite samples prepared through the co-precipitation method. The nominal compositions Co0.5Ni0.5−xMgx Fe2O4 in the range x = 0.1 have been synthesized and then was sintered at temperature at 700 and 1000°C in the furnace for 10 hour with a heating rate of 5°C/min. The prepared nanoferrites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and vibration sample magnetometer (VSM). XRD confirmed formation of single phase spinel ferrite with average crystalline size in the range of 27–33 nm. The lattice constant (a), cell volume (V) and X-ray density (ρx) are also calculated from XRD data. Lattice constant (a) decreases with an increase of sintering temperature. Further information about the structure and morphology of the nanoferrites was obtained from FESEM and results are in good agreement with XRD. Saturation magnetization showed increasing trend with sintering temperature from 700 to 1000°C.