Papers by Author: Kenji Suzuki

Abstract: The atomic scale structure of amorphous Si-C-O ceramics fibers produced from the pyrolysis of a polycarbosilane precursor has been investigated by X-ray diffraction using high-energy synchrotron radiation at SPring-8. First peak in the total correlation function T(r) of the amorphous and the heat-treated fibers is analyzed to consist of two contributions: Si-C (1.89 Å) and Si-O (1.61 Å) bonds. The coordination number of C and/or O around Si is about four. This suggests that the Si-C-O fibers basically have a network structure that consists of two tetrahedral units: SiC4 and SiO4. The local chemical and structural orders vary continuously in the materials from the disordered network structure of SiC4 and SiO4 tetrahedra (mixture of amorphous SiC and SiO2) to nanocrystals of SiC and SiO2, through the ternary Si-C-O solid solution which is believed to have an intermediate structure between the amorphous and crystalline states.

Abstract: Solution growth of 6H-SiC single crystal from Si-Ti-C ternary solution using the accelerated crucible rotation technique (ACRT) was performed. The SiC growth rate exceeding 200 μm/hr was achieved in several ACRT conditions. Such a high growth rate can be ascribed to the enhancement of the carbon transport from the graphite crucible to the growth interface due to the use of the ACRT. The incorporation of inclusions of Si-Ti solvent in the grown SiC crystal was also significantly suppressed by using the ACRT. The intensive convection near the growth interface induced by the ACRT resulted in not only the marked increase of SiC growth rate but also the superior homogeneity in the surface morphology. It was concluded that faster stable growth could be accomplished in the SiC solution growth using the ACRT. The obtained SiC self-standing crystal exhibited homogeneous green colour without cracks and inclusions. We investigated the crystalline quality of the grown SiC crystal by means of X-ray diffraction. The, ω-scan rocking curves of (0006) reflection measured by X-ray diffraction provided the FWHM of 15-20 arc-second showing the excellent crystallinity of the solution grown 6H-SiC single crystal.