Synchrotron X-ray diffraction studies of large sapphire crystal grown by Kyropoulos-like method



In this paper, monochromatic double-crystal X-ray diffraction and white-beam X-ray topography techniques using synchrotron radiation source were utilized to investigate the growth process of large sapphire crystal by an improved Kyropoulos-like method. Compared with the calculated theoretical value of 8.6 s, FWHM experimental values of sapphire are in the range of 11 ∼ 26 s, showing its good crystalline perfection in general, especially for the crystal in the central region of the boule. The analysis of white beam transmission X-ray topographs revealed the presence of dislocation tangles and helical dislocations in different crystal regions. The defect configurations in sapphire crystals were caused by the dislocation reaction and void formation.