X-ray topography and EPMA studies of synthetic quartz

Abstract

Characteristic growth patterns, observed on as-grown surfaces of hydrothermally grown synthetic quartz, were studied by combining Lang's diffraction topography and the electron probe micro analyzer (EPMA). A correspondence was recognized between the images of the optical surface topograph and the X-ray diffraction topograph. The causes of diffraction contrasts can be interpreted by the strain gradient owing to the segregation of impurities. By the EPMA studies, the following was found: (1) A1, Fe and Na are detected as impurities; (2) there is a clear topographic correspondence between the images formed by secondary electrons and the Kα fluorescence of Al and Fe; (3) the impurities precipitate preferentially along the grooves, and on the cobbled surface, and other imperfect skin layers detected by the diffraction topographs. The imperfect skin layer could be removed either by heavy etching or by mechanical polishing, the thickness being estimated to be several tens of microns. If the skin layer is eliminated, the diffraction topographs show that the interior is nearly perfect.