Abstract: Two different 6H-SiC single crystals were neutron-irradiated with different dose of 5.74×10~(18) n·cm~(-2),8.2×10~(18) n·cm~(-2) and 1.72×10~(19) n·cm~(-2) respectively, the damages caused by neutron irradiation were studied by X-ray diffraction. It is found that the damages in the samples with higher purity or in the samples annealed before irradiation are less than that in the samples which are with lower purity or un-annealed. The experimental results indicate that the creations of irradiation damages are not only decided on the irradiation fluences, but also are decided on the structure and the composition of the samples. The inherent defects and the impurity atom play an important role in the irradiation process as the "pinning", which result in the increasing of the long-range defects such as dislocations.

Key words: Two different 6H-SiC single crystals were neutron-irradiated with different dose of 5.74×10~(18) n·cm~(-2),8.2×10~(18) n·cm~(-2) and 1.72×10~(19) n·cm~(-2) respectively, the damages caused by neutron irradiation were studied by X-ray diffraction. It is found that the damages in the samples with higher purity or in the samples annealed before irradiation are less than that in the samples which are with lower purity or un-annealed. The experimental results indicate that the creations of irradiation damages are not only decided on the irradiation fluences, but also are decided on the structure and the composition of the samples. The inherent defects and the impurity atom play an important role in the irradiation process as the "pinning", which result in the increasing of the long-range defects such as dislocations.