Study On The Doping And Magnetic Properties Of Ni-Cu-Co And Ni-Mg-Co Nano-ferrite

Nowadays,with the rapid development of electronic information technology,the demand for information storage and magnetogen is increasingly severe.The cobalt nano-ferrite occupies half of the country.Among them,the research on Ni-Cu-Co and Ni-Mg-Co nano-ferrite is more prominent.Because these two kinds of nanomaterials have the characteristics of higher saturation magnetization,coercivity,residual magnetization,etc.This work mainly used non-magnetic element Al³⁺ions and transitional element Bi³⁺ions,non-magnetic Al³⁺ions doped or substituted Ni-Cu-Co nano-ferrite and Ni-Mg-Co nano-ferrite.The influence on Ni-Cu-Co and Ni-Mg-Co nano-ferrite lattice structure and magnetic properties were studied.This work mainly includes the following three contents:1.Using citric acid and nitrate as raw materials for sample preparation,Al³⁺ions doped Ni-Cu-Co nano-ferrite magnetic materials were prepared by the sol-gel method.The X-ray diffraction(XRD)was used to analyze the lattice structure of Al³⁺ions doped Ni-Cu-Co nano-ferrite materials.It is found that all Al³⁺ions doped samples have a single-phase cubic spinel structure.The average crystallite size is calculated by the Deby-Scherrer formula.It is found that the average crystallite size is between 46.1nm and 56.0nm.Fourier infrared spectroscopy(FT-IR)was used to further characterize the structure of Ni-Cu-Co nano-ferrite magnetic materials.It is found that the characteristic absorption peak?₁is near 585cm^-1,which also confirms that the Ni-Cu-Co nano-ferrite magnetic material have spinel structure.The shape and morphology of the nanoparticles,the chemical composition were analyzed by the energy dispersive X-ray spectrometer(EDX).The main magnetic properties of samples tested by the vibrating sample magnetometer(VSM).And the research found that when x=0.05,Ni-Cu-Co nano-ferrite has the best magnetic properties.Its Ms is 66.23 emu/g,Mr is 33.29 emu/g,and Hc is809.30 Oe.2.The Bi³⁺ions doped Ni-Mg-Co nano-ferrite magnetic material was prepared by the sol-gel method.Citric acid is complexing agent,high-purity nitrate and distilled water are experimental raw materials.The crystal lattice structure of the sample was analyzed using X-ray diffraction(XRD).The results show that when x=0 and x=0.025,the Bi³⁺ions doped Ni-Mg-Co nano-ferrite sample have single-phase cubic spinel structure.Other impurity peaks of Bi₂O₃appeared when‘x>0.025'.At the same time,it was also found that all samples had characteristic peaks of spinel structure.The average crystallite size of the sample is calculated by the Deby-Scherrer formula.In addition,the lattice constant increased from 8.3797(?)to 8.3940(?).Using Fourier Infrared Spectroscopy(FT-IR),the characteristic absorption band?₁of the spinel structure was observed at 584 cm^-1.Scanning electron microscope(SEM)images revealed that the powder sample was cubic and quasi-spherical.The chemical composition elements of Bi³⁺ions doped Ni-Mg-Co nano-ferrite were analyzed by energy spectroscopy(EDS).The vibrating sample magnetometer(VSM)were used to measure the important physical properties of the sample,it is found that the sample has ferromagnetic properties.In addition,the saturation magnetization(Ms)and residual magnetization(Mr)decreased with the increase of Bi³⁺ions content.The residual magnetization decreased from 28.75 emu/g to 17.96 emu/g,the saturation magnetization decreased from 60.59 emu/g to 51.95 emu/g.The results showed that Bi³⁺ions doping has the effect of reducing the magnetic properties of Ni-Mg-Co nano-ferrites.Meanwhile,it is found through the AC magnetization curve that when x=0.05,the best AC magnetic susceptibility H?Hm:67.09×10^-3emu/g Oe.3.Citric acid is used as a complexing agent,high-purity nitrate and distillation are used as raw materials for the experiment.The Al³⁺ions substituted Ni_0.2Mg_0.2Co_0.6Fe_2-xAl_xO₄(x=0.0,0.1,0.2 and 0.3)are prepared by sol-gel method.The X-ray diffraction(XRD)analysis showed that all samples have the characteristic peaks of spinel ferrite.It was also found that all nano-ferrite samples had single-phase structure,no other impurity phases were found.Fourier infrared spectroscopy(FT-IR)was used to further characterize the structure of Ni-Mg-Co nano-ferrite substituted by Al³⁺ions.There are two absorption bands?₁and?₂at 588cm^-1and 389cm^-1,respectively,which further proves that the sample has a spinel structure.The morphology of the sample was observed by a transmission electron microscope(TEM).The EDS was used to analyze the chemical composition of the sample.The elements Ni,Mg,Co,Fe,Al and O were found in the sample.It is analyzed by VSM that the Ni-Mg-Co nano-ferrites substituted by Al³⁺ions have ferromagnetic properties.With the increase of Al³⁺ions content,the saturation magnetization(Ms),residual magnetization(Mr),coercive force(Hc),anisotropy constant(K)and magnetic moment(?_B)all decrease.