Acta Metallurgica Sinica (English Letters) ›› 1999, Vol. 12 ›› Issue (5): 1136-1141.

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DIELECTRIC PROPERTIES OF NANO Si/C/N COMPOSITE POWDER AND NANO SiC POWDER AT HIGH FREQUENCIES AND MICROSTRUCTURE CHARACTERIZATION

D.L.Zhao, H.S.Zhao and W.C.Zhou State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072,China   

  • 收稿日期:1999-10-25 修回日期:1999-10-25 出版日期:1999-10-25 发布日期:2009-10-10

DIELECTRIC PROPERTIES OF NANO Si/C/N COMPOSITE POWDER AND NANO SiC POWDER AT HIGH FREQUENCIES AND MICROSTRUCTURE CHARACTERIZATION

D.L.Zhao, H.S.Zhao and W.C.Zhou State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072,China   

  • Received:1999-10-25 Revised:1999-10-25 Online:1999-10-25 Published:2009-10-10

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摘要： 1 . Introduction Nano m aterials are increasingly receiving recognition as practical structural and functional m aterials with good prospect , and have been developed extensively in recent years . The nano Si/ C/ Nco m posite po w der and nano Si C po w der have received an increasing interest since this kind of po wder could be synthesized by laser ? induced gasphase reaction . B....

Abstract: The dielectric properties of nano Si/C/N composite powder and nano SiC powder at high frequencies have been studied. The nano Si/C/N composite powder and nano SiC powder were synthesized from hexamethyldisilazane ((Me 3Si) 2NH) (Me:CH 3) and SiH 4 C 2H 2 respectively by a laser induced gas phase reaction. The complex permittivities of the nano Si/C/N composite powder and nano SiC powder were measured between 8 2GHz and 12 4GHz. The real and imaginary parts of the complex permittivities of nano Si/C/N composite powder are much higher than those of nano SiC powder. The SiC microcrystalline in the nano Si/C/N composite powder dissolved a great deal of nitrogen. The local structure around Si atoms changed by introducing N into SiC. Carbon atoms around Si were substituted by N atoms. So charged defects and quasi free electrons moved in response to the electric field, diffusion or polarization current resulted from the field propagation. The high ε″and loss factor tgδ(ε″/ε′) of Si/C/N composite powder were due to the dielectric relaxation.

Key words: nano Si/C/N composite powder, nano SiC powder, dielectric properties, microstructure