Study On Preparation And Doping Properties Of Ni-Cu-Co Ferrite Magnetic Materials

Magnetic materials in the field of materials science have become a subject of considerable interest in the field of electrical storage devices.In this paper,nano ferrite particles prepared by sol-gel auto combustion method have opened up new applications of magnetic materials,such as magnetic data storage in power electronics,magnetic targeting in the field of chemical drug carriers,and contrast agents in magnetic resonance imaging.At the same time,the magnetic properties of ferrite are greatly influenced by the particle size,particle size distribution and particle spacing.Due to low eddy current losses,nickel-copper-cobalt ferrites are widely used in power generation,conversion and regulation.In addition,they are more popular because of their high stability,low cost,light weight and small size.In this work,Ni-Cu-Co ferrite nanoparticles were systematically prepared by sol-gel auto combustion method,and their magnetic properties were analyzed and studied.The main work consists of three parts,which are as follows:1.Ni_0.2Cu_0.2Co_0.6Fe₂O₄ nanoparticles with different sintering temperatures were prepared by sol-gel auto combustion method.XRD analysis confirmed that all samples had single-phase cubic spinel structure.The particle size of the prepared samples ranged from 23 to 36 nm.The lattice constant and particle size increase with the increase of sintering temperature.FTIR spectra show that the characteristic peak v₁ is near 588 cm^-1.The results also confirm the formation of spinel structure.With the sintering temperature rising from 600 to 700?,the magnetic properties increase significantly.The increase of dM/dH peak height at H_m indicates the magnetic stability of cubic spinel samples with good crystallinity.2.The Y³⁺doped Ni-Cu-Co nanocrystalline ferrite with chemical composition of Ni_0.2Cu_0.2Co_0.6Fe_2-xY_xO₄?x=0.0,0.025 0.05,0.075,0.1?was prepared by sol-gel self ignition method.XRD data show that all samples show cubic spinel structure.The formation of spinel structure was also confirmed by FTIR measurements.With the increase of Y³⁺ doping amount,the tetrahedral absorption band moves to the high frequency side.EDX proved that the synthesized ferrite has pure phase and structure,and Y³⁺ ion doping was successfully realized.From the data of VSM,it can be seen that with the increase of doping amount,the Ms and Mr of the sample first increase and then decrease.When x=0.025,the maximum value is obtained,and the coercivity decreases after doping.Compared with pure samples and other doped samples,the best magnetic properties were obtained when the doping amount of Y³⁺ions was x=0.025.When the doping amount x=0.025,the switching field distribution?SFD?and the rectangular ratio?Mr/Ms?obtained the best performance.3.The bismuth doped Ni-Cu-Co ferrite was successfully synthesized by sol-gel self ignition method.XRD results show that Bi-doped Ni_0.2Cu_0.2Co_0.6Fe_2-xBi_xO₄?x=0.0,0.025,0.05,0.075,0.1?nanoparticles exhibit cubic spinel structure.The particle size of the prepared samples changed very little.FTIR measurements also confirmed the formation of spinel structure.At the same time,with the increase of bismuth content,the tetrahedral absorption band moves to the high frequency side.The morphology and particle size of the prepared samples were observed by TEM images at magnification.TEM images show that there are spherical cubic particles.EDX proved that the synthesized ferrite had pure phase and structure,and Bi³⁺doping was successfully realized.The cation redistribution in the synthesized spinel ferrite nanoparticles was observed by X-ray photoelectron spectroscopy?XPS?.All the chemical elements in the prepared samples existed in the appropriate valence state in the spinel ferrite lattice.With the increase of bismuth ion content,the magnetic properties of Ms,Mr and Hc decrease.It is observed that anisotropic constant?K?,magnetic moment and rectangular ratio?Mr/Ms?decrease with the increase of bismuth ion content.This indicates that the existence of particles in the non-conductive domain is consistent with the doping content.High porosity leads to high coercivity.For high density magnetic recording media,we usually need smaller SFD and larger rectangular ratio.We found that the switching field distribution?SFD?and rectangular ratio?Mr/Ms?of pure samples were the best.This indicates that Ni-Cu-Co ferrites doped with Bi³⁺ions have low magnetic properties.At the same time,it also shows that Bi-doped Ni-Cu-Co nanoferrites have low magnetic properties.