Two-dimensional small-angle X-ray scattering from as-grown and heat-treated synthetic quartz

Abstract

The small-angle X-ray scattering (SAXS) in as-grown and heat-treated quartz crystals was investigated as a function of the azimuth angle around the primary beam. For this, samples parallel to (10\bar 10) were extracted from Z- and −X-growth sectors of a synthetic quartz bar which had the OH content evaluated by infrared spectroscopy (IRS). In addition, SAXS and IRS were independently recorded as a function of heating temperature. As a result, the two-dimensional SAXS images revealed an anisotropic pattern randomly decorated by low-intensity Kossel lines. The intensities were projected along specific directions or were axially integrated around the primary beam. It was observed that the Porod invariant (Q) increased and the Kossel lines moved slightly to higher q values with increasing temperature. The effect of the sample orientation on the Q value and the lack of a clear relationship between Q and OH content suggested that the diffuse scattering due to the periodicity of the crystal lattice played an important role in the small-angle scattering of quartz. The net scattering intensities produced by heat-treatment at 873 K were attributed to molecular water aggregates created by the diffusion of as-grown OH defects.