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水合（铝）硅酸盐熔体（玻璃）的结构，以了解天然岩浆的行为，主要成果概述如下：1.多核、多熔体的发展。多维 NMR 技术是特别强大的结构工具，因为它们提供了有关原子连通性的直接信息，我们已经成功进行了各种 NMR 测量，包括 ^1H DQ（双量子）MAS。 NMR、^ 27 Al 3Q（三量子）MAS NMR、^ 27 Al-^1H HETCOR（异核关联）和3QMAS/HETCOR NMR。2.解决了有关聚合中水溶解机理的长期争议通过使用上述技术，我们已经证实水在聚合铝硅酸盐熔体中的溶解导致了。通过形成 SiOH/AlOH 使网络结构解聚。3.揭示硅铝酸盐熔体中水的成分依赖性……更多我们对一系列成分的系统研究，结合从头算计算，揭示了水的溶解。 (铝)硅酸盐熔体/玻璃中的反应涉及两个相互竞争的过程：(1) SiOH/AlOH 的形成和网络结构的解聚，以及 (2) 形成游离OH的形成和网络结构的聚合，其中四配位、五配位和六配位Al在水合钙硅铝酸盐玻璃和镁铝硅酸盐玻璃中共存，后者有利于解聚组合物。 4．高压含水矿物的核磁共振研究也对高压含水矿物进行了类似的研究，这不仅对于了解地幔矿物本身的结构具有重要意义。对含水熔体/玻璃的高压行为的见解。5.富^<17>O氧化物的合成方法的开发我们已经成功地合成了高产率的^<17>O富集氧化物。 ^ 17 O NMR测量有限数量的高压材料。