Development of the oscillation system for a micro-are monochromatic X-ray diffractometer.

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Studies on textural inhomogeneity like micro-domains and crystallites segregated from the host crystals are important for investigation of growing and/or cooling process recorded in the rock-forming and synthetic mineral crystals. The phenomena are usually examined by optical microscopy and/or electron-probe micro-analysis. Very limited number of such samples have been investigated so far by X-ray diffraction, because the samples (30μm in thickness) are mounted on sides 1.4mm thick (thin sections). The diffraction system with the micro-pinhole and been developed to measure diffraction from micro-domains with the monochromatic X-ray beam. The effective deameter of a micro-pinhole is 2.0μm for 0.7A^^° with a divergence 24μrad.In the previous experiment, we had difficulty with setting the sample position on the axis of rotation. Therefore an x-stage installed on a rotating stage of the sample has been prepared for setting the sample. The x-stage was controlled as the position of the sample setting on the micro-beam with a calibration curve determined before the experiments. However, the program to control the x-stage did not give the satisfying results, the improvement of the program is now in progress.To check the performance of the system, two kinds of thin sections were prepared for the diffraction experiments : one is a thin section of Cr-spinel crystals segregated from olivine host crystal in dunite from Iwanai-dake, Hokkaido, Japan and the other thin sections of the metamorphic rocks including jadeite, omphacite and riebeckite. The oscillation photographs of several kinds of mineral were successfully recorded on a flat imaging plate. The analysis of the diffraction data is now in progress.