Investigation of the lattice tilts at growth sector boundaries using double-crystal X-ray diffractometry

Abstract

It has been previously suggested that the lattice tilt between regions of a crystalline specimen having different impurity-induced unit-cell lengths depends on the angle of inclination of the boundary between the two regions. This hypothesis has ban investigated using double-crystal X-ray diffractometry in conjunction with a synchrotron radiation source. The relative tilts and dilatations have been determined in simple two-sector plates of synthetic quartz containing a – X/Z growth sector boundary inclined at different angles to their major surfaces. It was found that, to within the margins of experimental error, the angles of tilt between the adjacent regions obeyed the relation suggested previously. The results showed also that to within 1·0±0·7 seconds of arc there was no tilt between the –X and Z growth regions which would require the evocation of effects other than the difference in unit-cell lengths between the two regions to account for the observations. This work emphasizes the need to give consideration to specimen geometry, and particularly to the angle of inclination of the growth sector boundary in specimens when double-crystal diffraction studies are undertaken to evaluate crystal lattice perfection.