Study On The Structure And Magnetic Properties Of Ce³⁺ And Sm³⁺ Doped Ni-Co Ferrites

In this paper,using sol-gel method the ferrite of different rare earth ions doped system:Mg-Co ferrite,Ni-Zn-Co ferrite,Ni-Co ferrite.Through rare earth ion doping,the effects of different rare earth metals and different rare earth contents on spinel ferrite structure and magnetic properties were studied.Mainly from two work:1.Rare earth Ce³⁺doped Mg-Co ferrite and Ni-Zn-Co ferrite were prepared by sol-gel spontaneous combustion method.The chemical formula is as follows:Mg_0.2Co_0.8Fe_2-xCe_xO₄（x=0.00,0.025,0.05,0.075,0.1）and Ni_0.2Zn_0.1Co_0.7Fe_2-xCe_xO₄（x=0.00,0.025,0.05,0.075,0.1）.A series of common characterization methods were used to analyze the structure and properties of the samples.X-ray diffraction analysis shows that the prepared Ce³⁺doped Mg-Co ferrite and Ni-Zn-Co ferrite have spinel structure,and the grain sizes calculated according to Scherer formula belong to the size range of cubic spinel ferrite,and the lattice constants of the two systems will change within a certain range due to Ce³⁺doping.Fourier transform infrared spectrum analysis shows that the absorption bands of Ce³⁺doped Mg-Co ferrite samples appear in the range of 620 cm^-1and 410 cm^-1,and that of Ce³⁺doped Ni-Zn-Co ferrite samples appear in the range of 595 cm^-1.The absorption peaks of the samples in the two systems are consistent with the characteristics of spinel cubic ferrite.Combined with XRD results,it is confirmed again that the prepared rare earth Ce³⁺doped Mg-Co ferrite and Ni-Zn-Co ferrite have spinel structure.It is proved by elemental analysis that the proportion of main elements of rare earth Ce³⁺in Mg-Co ferrite and Ni-Zn-Co ferrite accords with the chemical formula of target sample.Scanning electron microscope images show that doping Ce³⁺does not affect the overall particle morphology of Mg-Co ferrite.Transmission electron microscopy（TEM）images show that doping Ce³⁺does not change the particle morphology of Ni-Zn-Co ferrite,and the particle samples are obviously spherical and cubic.VSM analyzed the magnetic properties of the two systems with different contents of rare earth ions.In Mg-Co ferrite,the continuous increase of Ce³⁺doping makes the magnetic parameters of nanoparticles:saturation magnetization（Ms）and remanent magnetization（Mr）increase first and then decrease,indicating that Ce³⁺doping Mg-Co ferrite has an effect on the magnetic properties of ferrite.When the concentration of Ce³⁺is 0.025,the saturation magnetization and remanent magnetization of nanoparticles reach the maximum value,and the magnetic properties of samples also reach the best value.In Ni-Zn-Co ferrite,Ms decreases gradually as the doping amount of Ce³⁺increase,while Mr and Hc increase first and then decrease.When the doping amount reaches 0.05,the magnetic properties of Ni-Zn-Co ferrite are the best,and the value of S also changes with the increase of the doping amount of Ce³⁺.The experimental results show that doping rare earth Ce³⁺can improve the magnetic properties and crystallinity of Mg-Co ferrite and Ni-Zn-Co ferrite,but does not change the structure of spinel.2.The rare earth Sm³⁺doped Ni-Co ferrite was selected,and the sol-gel spontaneous combustion method was used at room temperature.The sample composition was Ni_0.2Co_0.8Fe_2-xSm_xO₄（x=0.00,0.025,0.05,0.075,0.1）,and the sintering temperature was 950℃.XRD diffraction pattern analysis shows that the prepared nano ferrite particles have cubic spinel structure.Two absorption peaksν₁andν₂were determined by FTIR spectra,and the absorption peaks ranged from 580-610cm^-1 to 376-400 cm^-1.The positions of the two absorption peaks again confirmed that the prepared nano-ferrite particles had spinel structure,which was consistent with XRD results.TEM images showed that the prepared samples had spherical and cubic shapes.EDX image analysis showed that the main elements of the prepared ferrite nanoparticles were Ni,Co,Fe,O and Sm,and the pure sample did not contain Sm element,indicating that Sm element was successfully incorporated into nickel-cobalt ferrite.VSM image analyzes the magnetic properties of ferrite nanoparticles,and the hysteresis loops obtained confirm that Sm³⁺can change the magnetic properties of Ni-Co ferrite.When the content of Sm³⁺is 0.05,the magnetic properties of Ni-Co ferrite are improved compared with that of pure samples.The resulting ferrite nanoparticles are often used to prepare electronic devices.