抄録
High purity synthetic diamond crystals (type IIa) grown by the temperature gradient method with impurities less than 0. 1 ppm were studied on the crystal defects and residual strains in details by polarizing microscopy, double-crystal X-ray rocking curve measurement, X-ray topography and Raman spectroscopy. The results indicated that the synthetic type IIa diamonds had less crystal defects and lower residual strain than natural diamonds or synthetic type I b diamonds did. Furthermore it was found that some of dislocations in the synthetic type IIa diamond could be removed and the crystal quality of the diamonds could be improved by using strain-free and low defect crystals for the seeds.
