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Investigation of the structure and assembly of inorganic macromolecules formed on the terrestrial surface

研究陆地表面形成的无机大分子的结构和组装

基本信息

批准号：
17340160
负责人：
KOGURE Toshihiro
金额：
$ 10.28万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

There are a number of interesting natural materials on the terrestrial surface, formed in water-abundant and oxidizing conditions at moderate temperatures. These materials are generally very fine-grained and do not have three-dimensional periodicity, unlike common crystalline minerals. From these characteristics, they may be called "inorganic macro-molecules". However, their atomic structures and textures are not well understood, owing to the very small particle size and non-periodic structure. Imogolite, smectite and some phyllosilicates with heavy stacking disorder are typical examples. The purpose of this work was to develop new methodologies and/or techniques to investigate these materials, and elucidate their structures and forming conditions on the earth.At first, we tried to determine the atomic structure of imogolite, a natural nano-tube, from the intensity distribution in electron diffraction patterns. However, a plausible model that completely explains the electron diffractio … More n patterns was not obtained. This investigation must be continued as a future research. Meanwhile, Suzuki in AIST has made a progress in finding conditions to synthesize imogolite efficiently in a laboratory.Smectite is a very fine-grained phyllosilicate, often regarded as "nanosheet". Its basic structure is a 2:1 layer with two tetrahedral sheets and one octahedral sheet between them, but the detail is not clear yet. Especially distribution of octahedral rations in the 2:1 layer is under discussion. We investigated possibility to determine the cation distribution by using high-resolution electron microscopy (HRTEM). However, it was found that intense electron beam during image recording dehydroxylates the 2:1 layer and this dehydroxylation induces cation migration. We need to find an idea to overcome this problem in future. On the other hand, we have found a novel 2:1 layer structure in the thermally dehydroxylated phase of a kind of mica, celadonite.We have made a plenty of progress to elucidate the nature of stacking disorder in various phyllosilicates in this study, by using HRTEM and simulation of powder X-ray diffraction patterns. The investigated phyllosilicates include kaolin group minerals, pyrophyllite, talc, sudoite, etc. Especially direct observation of the stacking disorder in kaolin group minerals was an epoch-making work in the history of this topic started more than a half century ago.Besides, several new techniques and ideas to characterize the structure (stacking sequence, crystal orientation, morphology, etc.) of fine-grained materials using Kikuchi patterns were developed and demonstrated. Less

陆地表面有许多有趣的天然物质，它们是在充足的水和中等温度的氧化条件下形成的。与常见的晶体矿物不同，这些材料通常颗粒非常细，并且不具有三维周期性。从这些特性来看，它们可被称为“无机大分子”。然而，由于颗粒尺寸非常小和非周期性结构，它们的原子结构和织构还不太清楚。伊毛缟石、蒙脱石和一些具有严重堆积无序的层状硅酸盐是典型的例子。这项工作的目的是开发新的方法和/或技术来研究这些材料，并阐明它们的结构和在地球上的形成条件。首先，我们试图根据电子衍射图案的强度分布来确定伊毛缟石（一种天然纳米管）的原子结构。然而，尚未获得完全解释电子衍射图案的合理模型。这项调查必须作为未来的研究继续进行。与此同时，AIST的Suzuki在寻找在实验室中有效合成伊毛缟石的条件方面取得了进展。蒙脱石是一种非常细粒的层状硅酸盐，通常被视为“纳米片”。其基本结构是2:1层，中间有两个四面体片和一个八面体片，但细节尚不清楚。特别是2:1层中八面体比率的分布正在讨论中。我们研究了使用高分辨率电子显微镜 (HRTEM) 确定阳离子分布的可能性。然而，人们发现图像记录过程中的强电子束会使2:1层脱羟基，并且这种脱羟基会引起阳离子迁移。未来我们需要找到一个想法来克服这个问题。另一方面，我们在一种云母——青瓷石的热脱羟基相中发现了一种新颖的2:1层状结构。在这项研究中，通过使用HRTEM和粉末X射线衍射图模拟，我们在阐明各种层状硅酸盐中堆积无序的性质方面取得了很多进展。研究的层状硅酸盐包括高岭土族矿物、叶腊石、滑石、苏云石等。特别是直接观察高岭土族矿物的堆积无序性，在半个多世纪前的这一课题史上是一项划时代的工作。此外，还出现了一些表征细粒材料结构（堆积顺序、晶体取向、形貌等）的新技术和新思路。菊池模式被开发并展示。较少的