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纳米Si/C/N复相粉体的微波介电特性

赵东林 周万城 万伟

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纳米Si/C/N复相粉体的微波介电特性

赵东林, 周万城, 万伟

MICROWAVE PERMITTIVITY OF NANO Si/C/N OMPOSITE POWDERS

ZHAO DONG-LIN, ZHOU WAN-CHENG, WAN WEI
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  • 研究了纳米Si/C/N复相粉体在8.2—18GHz的微波介电特性,采用双反应室激光气相合成纳米粉体装置,以六甲基二硅胺烷((Me3Si)2NH)(Me∶CH3)为原料,用激光诱导气相反应法合成纳米Si/C/N复相粉体,复相粉体的粒径为20—30nm.纳米Si/C/N复相粉体与石蜡复合体的介电常量的实部(ε′)和虚部(ε″)以及介电损耗角正切(tan δ=ε″/ε′)随纳米粉体含量的增加而增大,ε′和ε″与纳米粉体体积分数(v)之间符合二次函
    The microwave permittivity of nano Si/C/N composite powders suspended in paraffin wax has been studied at the frequency range of 8.2—18GHz. The nano Si/C/N composite powders were synthesized from hexamethyldisilazane ((Me3Si)2NH) (Me:CH3) by a laser induced gas phase reaction. The dissipation factors of the nano Si/C/N composite powders are high at the microwave frequencies. The microwave permittivity of the mixture of nano Si/C/N composite powders and paraffin wax (or other dielectric materials) can be tailored by the content of the composite powders. And ε′, ε″ and tan δ increase with the volume filling factor ( v ) of nano Si/C/N composite powders. The ε′ and ε″ can be effectively modeled using second order polynomials ( ε′, ε″=Av2+Bv+C ). The ε′ and ε″ of the nano Si/C/N composite powders decrease with frequency at the frequency range of 8.2—18GHz. The difference being the microwave resonance is not sharply peaked but rather smeared out over a large frequency range. The promising features of nano Si/C/N composite powders would be due to more complicated Si, C, and N atomic chemical environment than in a mixture of pure SiC and Si3N4 phase. The SiC microcrystallines in the nano Si/C/N composite powders dissolve a great deal of nitrogen. The local structure around Si atoms changes by introducing N into SiC. Carbon atoms around Si are substituted by N atoms. So there exist a large number of charged defects and dangling bonds in the nano Si/C/N composite powders. Thus charged defects and quasi free electrons move in response to the electric field, diffusion or polarization current resulting from the field propagation. The high ε″ and dissipation factor tan δ(ε″/ε′) of Si/C/N composite powders are due to the dielectric relaxation.
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  • 文章访问数:  6469
  • PDF下载量:  1121
  • 被引次数: 0
出版历程
  • 收稿日期:  2000-07-16
  • 修回日期:  2001-06-28
  • 刊出日期:  2001-06-05

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