SYNTHESIS AND MICROSTRUCTURAL STUDIES OF FINE MAGNETIC PARTICLES

Abstract

In the present work fine Zinc, Manganese and Cobalt ferrites particles were prepared using the co-precipitation technique. The synthetic technique involved the co-precipitation of iron (Fe3+) and metal (zinc, manganese and cobalt) ions from aqueous solutions using NaOH base to create fine MFe2O4 particles (where M stands for metal). This technique provides greater homogeneity of the particles. The microstructural studies were performed using x-ray diffraction technique. Samples of zinc ferrites were synthesized at different digestion temperature. The concentrations kept at 0.2M. Spontaneous magnetization of the samples was determined by using permanent magnet. The Spontaneous magnetization of the samples decreased with increase in the digestion temperature of zinc (Zn2+). The maximum magnetization was found for samples having digestion temperature of 55oC. Particle sizes for the magnetic samples were determined using Sherrer’s formula. The XRD patterns of all the samples showed very close resemblance with the ICDD card data. The particle size was found to depend on the digestion temperature . Particle size of the samples increased with increase in the digestion temperature from 55oC to 85oC while it decreased for the digestion temperature of 95oC. The surface morphology and magnetic properties were also performed using SEM and VSM. The magnetic properties of zinc ferrite samples resembled those of ideal soft ferrite with almost no hysteresis loss. Fine manganese ferrite (MnFe2O4) particles were prepared using the co-precipitation technique. Samples with concentrations of 0.1 and 0.2 were prepared. The particle sizes of prepared samples were determined by using Scherrer’s formula. The surface morphology and magnetic properties showed that the particles were of narrow size distribution and have good properties of soft ferrites. In order to synthesize Cobalt ferrite particles, chemicals of FeCl3.6H2O, CoCl2.6H2O and NaOH were used. The magnetization of substituted ferrite nano particles synthesized by co-precipitation depends mostly on parameters such as reaction temperature, pH of the suspension, initial molar concentration etc. Cobalt ferrite samples were prepared from the mixed Fe2+ and Co2+ solutions, which were made from their stock solutions and had a constant initial total iron ions concentration and amounts of Co2+ ions. The size and size distribution was controlled by controlling the nucleation and growth rates. Magnetic nanoparticles of cobalt ferrite have been synthesized by wet chemical method using stable ferric and cobalt salts. X-ray Diffraction (XRD) confirmed the formation of single-phase cobalt ferrite nanoparticles in the range 15–48nm depending on the annealing temperature and time. The cobalt ferrite was also subjected to microwave which resulted in soft to semi hard ferrite transition. The size of the particles increases with annealing temperature and time while the coercivity goes through a maximum, peaking at around 28 nm In order to find the effect of variation in the metal ion to hydroxide ion ratio on particle sizes, we synthesized Cobalt ferrite particles using chemicals of FeCl3.6H2O, CoCl2.6H2O and NaOH. The magnetization of substituted ferrite nano particles synthesized by co-precipitation depends mostly on parameters such as reaction temperature, pH of the suspension, initial molar concentration etc. To find the transition temperature, the behavior of the specimen and the formation of phase of the magnetic material, resistively measurements were made on the sample. We may conclude that the co-precipitation technique has resulted in very good soft ferrites of zinc, cobalt and manganese. The crystallite sizes were varied by varying the concentration ratios, changing digestion times, varying digestion temperatures and applying microwave digestion. The magnetic properties were found to be dependent on the particle size. The surface morphology showed that the defects were not observed in the samples.