Crystallographic studies on interplanetary dust particles

本研究的目的是通过对美国宇航局航天飞机收集的行星际尘埃颗粒的分析，为太阳系的材料科学研究做出贡献。为了进行这项研究，我们鉴定了IDPs中包含的矿物，分析了它们的矿物结构和晶体的晶体畸变。下面描述了这两年所进行的结果、仪器和分析。在现有的衍射设备中，在移动工作台上安装锥形玻璃毛细管光学元件，以产生高强度的微光束.在现有的衍射设备中实现了成像板探测器代替X射线胶片读出系统的高空间分辨率.在KEK光子工厂，分别用多色和单色同步辐射的劳厄和振荡法获得了两种（Fe，Ni）硫化物离子掺杂的离子掺杂晶体（L2005 AE 6和L2005 AG 17）的衍射数据。经鉴定为NA型和3C型磁黄铁矿。前者具有沿着a轴的调制，后者具有沿着c轴的调制。它们是来自自然界的第一个例子，也就是说，它们是新矿物。后一种样品中除了3C型外，在衍射图上有明显的Debye-Scherrer线。本发明的3C-型的化学组成不同于其结构已经确定的合成3C-型。利用衍射图样中出现的两个异常缺反射条件，分析和确定了目前3C型的结构模型，并将研究结果作为特邀论文在1998年加拿大IMA会议、1998年马来西亚AsCA 98会议和1999年美国Denver会议上发表。

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.