Characterization of Verneuil red corundum by X-ray topography

Half boules of industrial red corundum (Al₂O₃) synthesized by the Verneuil process were cut into slices (about 1 mm thick) crosswise or lengthwise to the growth axis of the samples. All the slices were analyzed by optical microscopy, energy dispersive spectrometry (EDS) and by X-ray transmission topography. The samples turned out to be single crystals only at the bottom of the boule, corresponding to the initial stages of the growth. From the middle part of the boule considerable deformations leading to a macromosaic crystal were observed. In all of the examined samples the deformation vector showed a major component along a direction normal to the growth axis of the boule.