Crystallographic studies on interplanetary dust particles

这项调查的目的是在美国宇航局航天飞机收集的星际尘埃粒子(IDP)分析的基础上，为太阳系的材料科学做出贡献。为了开展这项研究，我们鉴定了国内流离失所者中的矿物，分析了矿物的结构，并分析了晶体的晶体变形。在现有的衍射设备中安装了移动台上的锥形玻璃毛细光学元件，以获得高强度的微光束。在现有的衍射设备中实现了高空间分辨率的成像板(探测器)读出系统。用劳厄法和振荡法分别用多色和单色同步辐射获得了两种IDPs(Fe，Ni)硫化物(L2005AE6和L2005AG17)的衍射数据。经鉴定为NA型和3C型磁黄铁矿。前者沿a轴调制，后者沿c轴调制。它们是自然界的第一个例子，即它们是新的矿物。在后一种样品中，除了3C型外，在衍射图上有明显的Debai-Scherrer谱线。目前的3C型化合物的化学组成不同于已确定其结构的合成的3C型化合物。分析了目前的3C型结构模型，并利用衍射图中出现的两个特殊的缺失反射条件进行了确定。这项研究的结果作为受邀论文分别在1998年的加拿大IMA会议、1998年的马来西亚AsCA98会议和1999年的美国丹佛会议上发表。

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.