Preparation And Magnetic Properties Of Ni_0.5Zn_0.5Fe₂O₄/BaFe₁₂O₁₉ Soft And Hard Magnetic Composites

In recent years,the requirement of electronic components is gradually increased with the rapid development of computer technology and electronic information technology,which making all kinds of electronic equipment to be highly integrating,multi-functionalization,miniaturization and rapid responsing.Meanwhile,the information exchange and storage system of electronic equipment is also growing into miniaturization and rapid storaging.Based on this background,magnetic nanocomposites with structures different from traditional structure have attracted extensive attention.The combination of soft and hard ferrites can provides unique properties,such as perfect exchange coupling behavior,larger surface area and wider absorption bandwidth,which makes them attractive for a variety of applications including microwave,recording media and medical treatment.In this paper,with the aim of high exchange coupling effect of hard and soft ferrite materials,the Ni_0.5Zn_0.5Fe₂O₄/Ba Fe₁₂O₁₉ nano powders was prepared by sol gel method with two steps,the Ni_0.5Zn_0.5Fe₂O₄/Ba Fe₁₂O₁₉nano film was deposited by pulsed laser deposition technique,and the Ni_0.5Zn_0.5Fe₂O₄/Ba Fe₁₂O₁₉nano array was prepared by pulsed laser deposition with assist of porous alumina mask template.The composition,microstructure,morphology and magnetic properties of the samples were characterized by a variety of characterization techniques.The results show that the composite has strong exchange coupling effect and broad application prospects in magnetic media and energy storage.The research results of this paper are as follows:（1）Studying the praparing method and properties of nano Ni_0.5Zn_0.5Fe₂O₄/Ba Fe₁₂O₁₉ composite powders based on the sol-gel method.Firstly,nano Ba Fe₁₂O₁₉ ferrite powder was prepared by sol-gel method.Then,the nano Ba Fe₁₂O₁₉ ferrite powder is mixed with the unsintered Ni_0.5Zn_0.5Fe₂O₄ gel.The soft and hard magnetic composite powders of Ba Fe₁₂O₁₉+x（wt）%Ni_0.5Zn_0.5Fe₂O₄,（x=5,10,15,20,25,30,35,40）were prepared in two steps.Finally,the composite powder was characterized.The results show that the two phases are well dispersed and the agglomeration is weak.The exchange coupling effect of x=25,30,35,40 is obviously weaker than that of x=5,10,15,20.Saturation magnetization,residual magnetization and maximum magnetic energy product all increase first and then decrease with the increase of soft magnetic phase components.The maximum saturation magnetization,residual magnetization and magnetic energy product of x=20 are 58.9 emu/g,30.5 emu/g and 1.16MG.Oe,respectively.It displays a certain application prospect in magnetic storage field.（2）Studying the preparation method and properties of PLD growth Ni_0.5Zn_0.5Fe₂O₄/Ba Fe₁₂O₁₉ nanocomposite thin film.Firstly,two nano Ni_0.5Zn_0.5Fe₂O₄/Ba Fe₁₂O₁₉composite films were prepared by using PLD technology,sample A(3 layers of Ni_0.5Zn_0.5Fe₂O₄ and 3 layers of Ba Fe₁₂O₁₉)and sample B(4 layers of Ni_0.5Zn_0.5Fe₂O₄ and 4 layers of Ba Fe₁₂O₁₉);Secondly,the structure and morphology of the composite film were characterized,which showed clear interfaces between the films,and the composite film has a smooth surface and high crystal quality.Finally,through the characterization of magnetic properties of the composite film,it is shown that the composite film has certain anisotropy and strong exchange coupling effect in the vertical direction of the film plane,and the remanence ratio reaches 0.55（sample A）and 0.59（sample B）.（3）Studying the preparation method and properties of Ni_0.5Zn_0.5Fe₂O₄/Ba Fe₁₂O₁₉nano array by PLD with ultra-thin AAO mask.Firstly,an ultra-thin AAO template with pore spacing of 450 nm,pore diameter of 350 nm and thickness of 1μm was successfully prepared in phosphoric acid system by the secondary anodic oxidation method.The template was transferred to alumina substrate.Secondly,two Ni_0.5Zn_0.5Fe₂O₄/Ba Fe₁₂O₁₉ nano array films were prepared by using PLD technology with the assits of AAO mask and step by step annealing method,sample A(3 alternant layers of Ni_0.5Zn_0.5Fe₂O₄ and Ba Fe₁₂O₁₉)and sample B(4 alternant layers of Ni_0.5Zn_0.5Fe₂O₄ and Ba Fe₁₂O₁₉);Finally,the properties of the samples were characterized.The results show that the preparation of Ni_0.5Zn_0.5Fe₂O₄/Ba Fe₁₂O₁₉ array structure own a small of nano point interval,and high continuity.At the same time,Ni_0.5Zn_0.5Fe₂O₄/Ba Fe₁₂O₁₉nano array has an obvious of anisotropic and a stronger exchange coupling effect in the vertical direction.The remanence ratio reached 0.57 for sample A and 6.0 for sample B,displaying a certain improvement compared with the composite film.