Development of Magnetoplunbite Type Ferrite Electromagnetic Absorber in the Frequency of GHz

GHz波段的近入射微波辐射越来越多地应用于各种通信设备中。然而，这带来了电磁干扰（EMI）的问题。目前，m型钡铁氧体有望成为对抗电磁干扰的有力手段。我们最近的研究表明，m型Ba铁氧体是一种很有前途的GHz微波吸收材料。磁共振吸收特性取决于复磁导率μ=μ′-jμ′，特别是虚部μ′=Ms/2Haα。（Ms：饱和磁化强度，Ha：各向异性场，α：消光系数），复容率ε=ε′-jε′”。在Ba Fe_<12-x> (Ti_<0.5>Mn_<0.5>)_xO_<27>化合物中获得了较高的复渗透率μ”。其中Fe^<3+>被（Ti_<0.5>Mn_<0.5>）取代。由于六方铁氧体表现出单轴各向异性，可以预期，在磁场中使用压机排列样品可以提高样品的微波吸收性能。在本研究中，我们用IV族的Mn（II）和Ti， Zr和Sn代替Fe^<3*>在bfe_ <12-x> (Me_<0.5>Mn_<0.5>)_xO_<27>:(Me: Ti, Zr, Sn) （x=0-4.0）化合物中。采用常规粉末冶金方法制备样品，并将样品制成c轴垂直于样品厚度的环形。然后研究了饱和磁化强度Ms和Me离子（Me: Ti）对Fe^<3+>的取代组成(x)的影响。Zr, Sn)对Ba Fe_<12-x> (Me_<0.5>Mn_<0.5>)_xO_<27> (Me: Ti, Zr, Sn)化合物电磁吸收性能的影响。利用VSM和网络分析仪测量了磁性能和共振吸收特性（μ’、μ’等）。排列后的Ti-、Sn-和Zr-取代样品的μ”值分别为4.4、5.1和5.7，匹配厚度d_m分别为0.9mm、0.6mm和0.4mm。这些μ”值明显大于各向同性（TiMn）取代样品的3.8。因此，六方铁氧体中Ti、Sn、Zr、Mn等金属离子的取代和c轴排列对提高m型铁氧体吸收体的电磁波吸收特性是有效的。少

Recentry Microwave radiation in the GHz band is increasingly being used in many various communication devices. However, this has brougt about the problem of electromagnetic interference (EMI). Now M-type Ba ferrite is expected to be used as a powerful countermeasure to EMI.Our recent works have shown that M-type Ba ferrite is a promising material for microwave absorber in the GHz range. The magnetic resonance absorption properties depend on the complex permeability μ=μ'-jμ" particularly the imaginary part μ"=Ms/2Haα. (Ms : saturation magnetization, Ha : anisotropic field α : extinction coef.) and the complex permissivity ε=ε'-jε". A high complex permeability μ" has been obtained in Ba Fe_<12-x> (Ti_<0.5>Mn_<0.5>)_xO_<27> compound. in which Fe^<3+> was substituted by (Ti_<0.5>Mn_<0.5>). And As hexagonal ferrite exhibits a uniaxial anisotropy, it may be expected that the microwave absorption properties would be enhaned if the sample are aligned using the press in magnetic field. In this … More study we used Mn(II) and Ti, Zr and Sn of Group IV as substitute for Fe^<3*> in BaFe_<12-x> (Me_<0.5>Mn_<0.5>)_xO_<27> : (Me : Ti, Zr, Sn) (x=0-4.0) compound. The sampls were prepared by conventional powder metallurgy method and were formed into toroidal shapes whose c-axis were aligned vertically to the sample thickness. Then we investigated the effects of saturation magnetization Ms and substitution composition (x) of Me for Fe^<3+> by Me ion (Me : Ti.Zr, Sn), on the electromagnetic absorption properties of the Ba Fe_<12-x> (Me_<0.5>Mn_<0.5>)_xO_<27> (Me : Ti, Zr, Sn) compound. The magnetic properties and the resonance absorption characteristics (μ', μ" etc) were measured using a VSM and a network analyzer. The aligned Ti-, Sn- an d Zr- substituted samples showed values of μ"=4.4, 5.1, 5.7 and matching thickness d_m=0.9mm, 0.6mm, 0.4mm, respectively. These μ" values is significantly larger than 3.8 for isotropic (TiMn)-substituted samples. It is therefore concluded thatt the metal ion substitution such as Ti, Sn, Zr and Mn and the c-axis alignment in hexagonal ferrite are effective in enhancing the electromagnetic wave absorption characteristics of M-type ferrite absorber. Less