The Study Of The Structure And Electromagnetism Parameters Of Ferrites Prepared By The Citrate Method

With the development of RF communication, various electronic equipments,SPC exchanges and mobile communication equipments are applied widely . The EMI phenomenon becomes more and more serious.It has a great influence on the normal work of electronic systems and it is causing damage to the health of humankind.As a kind of absorbing material,ferrites are not only magnetic medium but also dielectric medium,so they have the function of magnetic absorption and dielectric absorption.Compared to other absorbing materials,they have the advantage of strong absorption,broad wave band and low cost,so they are widely used in the realm of the civil and military application.The citrate method as a solution-based method,which allows mixing of precursors at the molecular level,is advantaged in the preparation of ultra-fine materials.Rare-earth element has non-coupled 4 f electrons shielded by the outmost shell electrons,so its atoms and ions have special electromagnetism performances.The electromagnetism parameter can be adjusted by use of the character of Rare-earth element. In this paper,the nano-power of ferrites Ni_1-xZn_xFe₂O₄ (x=0.2,0.35,0.5) with spinel structure and hexagonal ferrites Ba3Co2RexFe24-xO41 with planar structure (Re=La,Gd, x=0,0.1,0.3) are synthesized by the citrate method.The structure and pattern of the ferrite powder were studied by means of XRD and SEM;Also,vector network analyzer is performed to measure the electromagnetism parameters of Ni-Zn Ferrites,Co₂Z ferrites and Ba₃Co₂Re_xFe_24-xO₄₁ (Re=La,Gd) ferrites at the microwave band.The results show that,1,The image part of the permittivity of synthesized powders is small;the real part of the permittivity of Ni-Zn ferrite increases with the increasing amount of zinc.2,The real part of the permeability of synthesized powders decreases with the increasing amount of zinc at the range of 2⁹GHz but vary small at the range of 9¹8GHz; the imaginary of the permeability decreases with the increasing amount of zinc.3,The rare earths doped in Z type ferrites increase the real and image part of the permittivity of Z type ferrites,and it vary with the doping amount of the rare earths;when the doping amount of these two rare earths is 0.1,the real part of the permittivity of Z type ferrites with La ions and Gd ions doped shows a little different;for the image part of the permittivity,the rare earths doped in ferrites enlarge it,and the effect of Gd ions is greater than La ions.4,The rare earths doped in ferrites have a great influence on the real and image part of the permeability,when the doping amount of these two rare earths is 0.1,Gd ions doped in ferrites increase the real part of the permeability,and inversely for La ions.For the image of the permeability,La ions doped in ferrites will reduce it;and Gd ions doped in ferrites reduce it only at the range of greater than 1GHz,at the range of less than 1GHz,Gd ions doped in ferrites enlarge it.