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Unraveling the structure of high-pressure hydrous silicate melts by multi-dimensional NMR spectroscopy and ab intio calculations

通过多维核磁共振波谱和从头计算揭示高压水合硅酸盐熔体的结构

基本信息

批准号：
17340164
负责人：
XUE Xianyu
金额：
$ 8.19万
依托单位：
Okayama University
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 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17340164/
关键词：
melt glass structure water NMR aluminosilicate high pressure ab initio calculation 鉱物

项目摘要

The purpose of this study was to unravel the structure of hydrous (alumino)silicate melts (glasses) at high pressure in order to understand the behavior of natural magmas. The main achievements are outlined below:1.Development of multi-nuclear, multi-dimensional NMR techniques. Multi-dimensional NMR techniques are particularly powerful structural tools because of the direct information they provide about atomic connectivities. We have succeeded in a variety of NMR measurements including ^1H DQ (double quantum) MAS NMR, ^<27>Al 3Q (triple quantum) MAS NMR, and ^<27>Al-^1H HETCOR (heteronuclear correlation) and 3QMAS/HETCOR NMR.2.Settling a long-term controversy concerning the water dissolution mechanism in polymerized aluminosilicate melts. By using above techniques, we have confirmed that the dissolution of water in polymerized aluminosilicate melts results in the depolymerization of the network structure through formation of SiOH/AlOH.3.Unraveling the compositional dependency of water … More dissolution mechanisms in aluminosilicate melts. Our systematic study over a range of compositions, coupled with ab intio calculations, has revealed that the dissolution of water in (alumino)silicate melts/glasses involves two competing processes : (1) formation of SiOH/AlOH and depolymerization of the network structure, and (2) formation of free OH and polymerization of the network structure, with the latter favored by depolymerized compositions with cations of large field strength. Four-, five-and six-coordinate Al were found to coexist in hydrous Ca-and Mg-aluminosilicate glasses.4.NMR study of high-pressure hydrous minerals. A similar study was also carried out on high-pressure hydrous minerals. This is not only important for understanding the structures of mantle minerals themselves, but also provided insights into the high-pressure behavior of hydrous melts/glasses.5.Development of synthesis method for ^<17>O-enriched oxides. We have succeeded in synthesizing ^<17>O-enriched oxides with high yield. This is essential for ^<17>O NMR measurements on high-pressure materials of limited quantity. Less

本研究的目的是揭示高压下含水（铝）硅酸盐熔体（玻璃）的结构，以了解天然岩浆的行为。主要成果如下：1.多核多维核磁共振技术的发展。多维NMR技术是特别强大的结构工具，因为它们提供了关于原子连接性的直接信息。我们成功地进行了一系列的核磁共振测量，包括^1H DQ（双量子）MAS NMR，^<27>Al 3Q（三量子）MAS NMR，以及^<27>Al-^1H HETCOR（异序相关）和3QMAS/HETCOR NMR。2.解决了聚合铝硅酸盐熔体水溶解机理的长期争论。通过上述技术，我们证实了水在聚合铝硅酸盐熔体中的溶解通过形成SiOH/AlOH而导致网络结构的解聚。3.解开水的组成依赖性 ...更多信息铝硅酸盐熔体中的溶解机制。我们对一系列组成的系统研究，加上abintio计算，揭示了水在（铝）硅酸盐熔体/玻璃中的溶解涉及两个竞争过程：（1）SiOH/AlOH的形成和网络结构的解聚，和（2）游离OH的形成和网络结构的聚合，后者有利于解聚的组合物与阳离子的大场强。在Ca和Mg铝硅酸盐玻璃中发现了四配位、五配位和六配位Al共存。4.高压水合矿物的NMR研究。对高压含水矿物也进行了类似的研究。这不仅对了解地幔矿物本身的结构有重要意义，而且对了解含水熔体/玻璃的高压行为也有重要意义。5.富氧氧化物合成方法的发展<17>。我们成功地合成<17>了高产率的富氧氧化物。这对于<17>在有限数量的高压材料上进行~ 1H NMR测量是必不可少的。少