Study On Doping Properties Of Ni-Cu-Co Ferrite Nanomagnetic Materials Prepared By Sol-gel Method

Nickel-copper-cobalt ferrite is a kind of ferrite material with unique physical and chemical properties.It plays a very important role in magnetic materials.Meanwhile,it also has mixed spinel crystal structure of metal oxide magnetic ceramics,and shows very good chemical,mechanical,electrical,magnetic and optical magnetic properties.Nickel copper cobalt ferrite has been widely used in magnetic recording,electrical storage equipment,microwave absorbing materials,biomedicine and other fields due to its high coercive force,high frequency permeability,magnetocrystalline anisotropy constant,excellent chemical and corrosion resistance.In this paper,the magnetic La³⁺ions and Mn²⁺ions doped nickel-copper-cobalt ferrite were synthesized by sol-gel method,and nickel copper cobalt nano ferrites were synthesized by using different complexing agents,and their magnetic properties were analyzed and studied.The main work consists of three parts,which are as follows:1.Lanthanum doped Ni-Cu-Co nanoferrites with the chemical composition Ni_0.2Cu_0.1Co_0.7Fe_2-xLa_xO₄?x=0.0,0.025,0.05,0.075,0.1?were prepared by sol-gel auto-combustion technology.All samples were sintered at a temperature of 950?.The X-ray diffraction?XRD?analysis verifies that all the samples of the formation of the cubic spinel structure.It turns out that with the addition of La³⁺ions,the lattice constant decreases,and with the addition of La³⁺ions,the lattice constant increases.The obtained Fourier transform infrared?FTIR?measurement also confirms the formation of the spinel structure.With the increase in La³⁺ions,the higher frequency?₁ is slightly moving towards the high-frequency side.Transmission electron microscopy?TEM?images show the presence of particles which are spherically cubic shaped crystallites.The presence of constituent's,i.e.,the presence of ingredients,namely,Ni,Cu,Co,Fe and La were authenticated by Energy dispersive x-ray analysis?EDX?.It was confirmed La³⁺-doping was successfully achieved.The magnetic parameters were measured by Vibrating sample magnetometer?VSM?.The saturation magnetization,remanent magnetization,coercivity,anisotropy constant first increase and then decrease with the La³⁺ions content increases.The samples had the best magnetic properties when the adulteration content of La³⁺ions at x=0.025.This indicates that appropriate doping can improve the magnetic properties of the samples.The reduction of the magnetic moment can be attributed to non-magnetic La³⁺ions in place of Fe³⁺ions?5?_B?,which results in a reduction of net total magnetic moment.2.Manganese substituted Ni-Cu-Co nanoferrites with the chemical composition Ni_0.2Cu_0.2Co_0.6-x.6-x Mn_xFe₂O₄?x=0.0,0.1,0.2,0.3,0.4?were prepared by sol-gel auto combustion method.The effect of Mn²⁺ions substitution on structural and magnetic properties of nickel-copper-cobalt ferrite has been studied.All the prepared samples show that the single-phase cubic spinel structure by X-ray diffraction?XRD?.Fourier transform infrared?FTIR?measurements also confirm the formation of the spinel structure of ferrite,and with the increase of manganese content,the peak of the Fe-O bond moved to low frequency.The prepared samples were observed to have spherically cubic shaped crystallites particles by transmission electron microscopy?TEM?.Energy dispersive X-ray?EDX?confirmed that the synthesized ferrite had pure phase and structure,and Mn²⁺-doping was successfully achieved.The magnetic properties of Mn²⁺ion substituted for nickel-copper-cobalt ferrite were studied by Vibrating sample magnetometer?VSM?.The saturation magnetization,coercivity,magnetic moment and anisotropy constant first increase and then decrease as the Mn content increases.When the content of Mn²⁺ions is 0.1,the maximum values of saturation magnetization and coercivity are 61.95 emu/g and 689.76 Oe,respectively.Compared with pure sample and other substituted samples,the better magnetic properties were obtained when the substitution amount of Mn²⁺ions was x=0.1.This indicates that the magnetic properties of ferrites can be improved by substituting manganese with the appropriate amount.However,the ferrite ferromagnetism is weakened due to excess Mn²⁺ions substitution.And the prepared ferrites are suitable for magnetic storage devices.3.Sol-gel auto combustion method?EDTA,egg white,oxalic acid,tartaric acid and citric acid as a complexing agent?was used to prepare Ni-Cu-Co ferrite nanoparticles with the chemical composition of Ni_0.2Cu_0.1Co_0.7Fe₂O₄.The phase formation has been confirmed by XRD patterns,which is a characteristic of spinel ferrite with most intense?311?peak.The crystallization of the material in the cubic spinel structure,the lattice parameter is approximately 8.38?.Different complexing agents have great influence on the average crystallite size?30�40 nm?of samples.The formation of spinel structure was also confirmed by Fourier transform infrared?FTIR?measurements.Scanning electron microscopy?SEM?and transmission electron microscopy?TEM?images indicates the existence of spherical cubic particles.The synthesized samples were demonstrated by energy dispersive X-ray?EDX?to have pure phase and structure,Ni,Cu,Co,Fe,and O were the main elements in Ni_0.2Cu_0.1Co_0.7Fe₂O₄.Confirmed by X-ray photoelectron spectroscopy?XPS?cation redistribution of spinel ferrite nanoparticles.The magnetic parameters were measured by Vibrating sample magnetometer?VSM?.Hysteresis curve of the ferromagnetic behavior observation confirmed these samples.Compared with the samples prepared with other complexing agents?EDTA,egg white,tartaric acid and citric acid as complexing agents?,the maximum of saturation magnetization and remanent magnetization were obtained for the sample prepared with oxalic acid as complexing agent.These ferrites have high coercivity.The sample prepared with oxalic acid has better magnetic properties than those samples prepared with other complexing agents.This indicates that oxalic acid as a complexing agent has stronger complexing ability for samples and less hydrolysis of metal ions in precursor solution than other complexing agents.