Crystallographic studies on interplanetary dust particles

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The aim of this investigation is to contribute materials science of the solar system based on analyses of the interplanetary dust particles (IDPs) collected with space shuttle by NASA. In order to carry out this study, we identify minerals included in IDPs, analyze their textures of minerals and also crystallographic distortion of crystals.The results, instrumentation and analyses, performed in this two years are described below.1. Tapered glass capillary optics on the moving stage is installed in the existing diffraction equipment to make micro-beam with high intensities.2. High spatial resolution of imaging plate)detector instead of X-ray film) readout system is achieved in the existing diffraction equipment.3. Diffraction data of two (Fe, Ni) sulfides of IDPs (named L2005AE6 and L2005AG17) are obtained by Laue and oscillation method using polychromatic and monochromated synchrotron radiation respectively at the Photon Factory, KEK. They are identified to be NA-type and 3C-type of pyrrhotite. The former has modulation along a-axis and the latter along c-axis. They are first examples from nature, I.e. they are new minerals. Beside 3C-type in the latter sample by four week but distinct Debye-Scherrer lines in the diffraction pattern. The chemical composition of the present 3C-type is different from that of synthetic 3C-type of which structure is already determined. The structure model of the present 3C-type is analyzed, and determined by making use of two extraordinary conditions of missing reflections exhibited in the diffraction pattern.The results obtained by this investigation are presented at IMA meeting, Canada, 1998, at AsCA98, Malaysia, 1998, and Denver meeting, USA, 1999 as invited papers.