Abstract:Nano-SiC powders doped by B were synthesized through the carbothermal reduction of xerogels containing the tributyl borate. The results show that the 3C-SiC with minor phase of 6H-SiC is generated at 1 700 ℃, and that there are not the characteristic peaks of any boride in the XRD patterns, which indicates that the boron is available only on the crystallization of 3C-SiC. The Raman spectra of the samples also show the characteristic bands of 3C- and 6H-SiC at 788 and 965 cm⁻¹. But the bands at 1 345 and 1 590 cm⁻¹ are characteristic peaks of amorphous carbon materials. The intensities of peaks at 788 and 965 cm⁻¹ increase with B content in Raman spectra, which also shift to higher wavenumber with the increasing B. The microstructure of SiC powder is composed of agglomerated particles with diameters ranging from 30 to 100 nm. The results of dielectric property show that the sample with 0.005 B has the largest values in ε′ and ε″ among the four samples due to the existence of the intrinsic defects. But the absence of the relaxation polarization leads to low values of all the samples.

Key words: SiC powder; sol-gel; B dopant; dielectric property; Raman spectroscopy