جستجوی مقالات مرتبط با کلیدواژه « Cation Distribution » در نشریات گروه « مواد و متالورژی »

Nickel doped CoMn ferrites with high magnetization were synthesized by double sintering solid state route with compositions of Co0.7-xNixMn0.3Fe2O4 with x = 0, 0.05, 0.1 and 0.15. Theoretical Cation distribution for cubic spinel ferrites was suggested on basis of electrical configuration expectations and cation site preferences. Cation distribution suggested was in good agreement with experimental results obtained from VSM and XRD. Values of theoretically calculated magnetic moment, coercivity and magnetization are in good agreement with experimental data obtained from VSM. Maximum saturation magnetization of 37.7emu/gm is obtained for sample Co0.7Mn0.3Fe2O4 at magnetic field of 5K Oe. Magnetostriction was found to increase with increasing magnetic field (from 1KOe to 5KOe.) Maximum magnetostriction of 84ppm was observed for sample Co0.7Mn0.3Fe2O4 at 5KOe. Maximum magnetization of magnetoelectric composites with 30% Co0.7-xNixMn0.3Fe2O4 – 70% PbZr0.48Ti0.52 was found to be 7.4 emu/g for composition with x = 0.

Current study represents the effect of the size and synthesis method on the cation distribution of cobalt ferrite nanoparticles and on the magnetic properties. The nanoferrites have been synthesized through sol-gel auto-combustion method using metal nitrates as precursor and citrate as fuel. In order to obtain the fine and agglomerated-free particles, we have used salt-assisted combustion reaction method. Magnetic properties of the synthesized single phase cobalt ferrite nanoparticles are carried out using vibrating sample magnetometer (VSM) at room temperature. It has been observed that the coercivity and saturation magnetization of the samples reduced by adding salt. The transmission electron microscopy (TEM) confirms the finer nanoparticles formation from around 70-200 nm to 10-40 nm. Structural characterization is done by X-ray diffraction (XRD) and it confirms the spinel structure formation for the samples. The crystallite size and induced strain were derived from the XRD patterns by Williamson-Hall (W-H) method. The magnetic parameters were reduced by crystallite size reduction from 38.5 nm to 11 nm. The further analysis of XRD peaks is fulfilled using Rietveld refinement in order to explain the magnetic properties. The obtained Rietveld refined data allow us to measure the distribution of cations within the available octahedral and tetrahedral sites.

In this work, the different fuels (citric acid, glycine and urea) were used for solution combustion synthesis of CoFe2O4 powders. X-ray diffraction, Raman spectroscopy, electron microscopy and vibrating sample magnetometry techniques were employed for characterization of phase evolution, cation distribution, microstructure and magnetic properties of the as-combusted CoFe2O4 powders. Single phase CoFe2O4 powders with partially inverse structure in which the Co2 cations are distributed in both tetrahedral and octahedral sites were synthesized by the citric acid, glycine and urea fuels. The as-combusted CoFe2O4 powders by the citric acid fuel exhibited the highest inversion coefficient. The crystallite size of the as-combusted CoFe2O4 powders synthesized by urea fuel was 15 nm, increased to 41 and 52 nm for the glycine and citric acid fuels, respectively. Furthermore, the solution combusted CoFe2O4 powders showed ferromagnetic behavior with saturation magnetization of 61.9, 63.6 and 41.6 emu/g for the citric acid, glycine and urea fuels, respectively. The high crystallinity and particle size of the as-combusted CoFe2O4 powders using glycine fuel led to the highest magnetization and the moderate coercivity.