Hydrous Components in Nominally Anhydrous Phases

标称无水相中的含水组分

• 批准号: 2149559
• 负责人: George Rossman
• 金额: $ 39.03万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-03-01 至 2025-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2149559&HistoricalAwards=false
• 关键词: Hydrous; Components; Nominally; Anhydrous; Phases

Hydrogen exists as a minor component in numerous crystalline substances as molecular water and hydroxide ions, the so-called hydrous components. Minerals with these components include those that make up the Earth and synthetic industrial analogues that are of technological importance. The hydrogen in Earth’s minerals account for the vast majority of our planet’s hydrogen and has a profound effect on the behavior of Earth’s interior. Similarly, hydrous components can significantly modify the material properties of synthetic materials, such as semiconductors. Despite the clear importance of hydrogen in these contexts, there remain two fundamental uncertainties: 1) where does the hydrogen incorporate into crystal structures and 2) at what concentrations hydrogen is present. This work will address both issues through a comprehensive approach of both laboratory experiments and computer simulations. This will include development of analytical techniques for hydrogen detection, detailed spectroscopic studies, and interpretation of experimental data from quantum mechanics calculations. In addition to continuing work on previously studied silicate minerals (the most abundant minerals in the earth), the research will also focus on binary oxide minerals. Binary oxides are not only geologically relevant, but also have extreme relevance in many established and emerging technologies, ranging from solar cells, to lasers, touch screens, pigments, semiconductors, and flat screen displays. Hydrogen impurities have been shown to play a key role in these settings. Thus, this research will not only be important for understanding the inner workings of our planet, but will also be significant for the development of new technologies.It has long been understood that hydrous components (OH- and H2O) in nominally anhydrous minerals (NAMs) are of great importance in earth science. These phases, which include abundant mantle phases such as olivine, garnet, pyroxene and ringwoodite, are likely the largest reservoir for hydrogen in the Earth. The trace hydrogen in NAMs often has outsized effects on a wide range of their material properties, from melting points, to mechanical deformation, thermal and electrical conductivity, color, radiation stability. Despite the clear significance of hydrogen in NAMs, there persist two fundamental issues. First is the quantification of hydrogen concentrations in these phases. Numerous techniques have been attempted or utilized over the last few decades including nuclear profile analysis and SIMS measurements, but the technical challenges related to measuring trace hydrogen concentrations in NAMs have proven difficult to overcome. Second is the identification of specific hydrogen sites in NAMs. Although some defect sites have been identified in specific NAMs such as garnets, there is little recourse for establishing the detailed defect structures in most phases. Our proposed solution to these issues is a holistic approach that considers both established and emergent techniques for measuring trace hydrogen in minerals, and quantum mechanics (density functional theory) calculations. These research components will be linked through infrared spectroscopy of oriented crystals, a technique that has proven fundamental in the study of NAMs. Our work will initially focus on simple oxide minerals such as rutile and stishovite, a group of phases that has typically been underrepresented in research into NAMs, but whose study could greatly benefit the field as a whole, with additional benefits to the development of technological materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

氢以分子水和氢氧根离子的形式存在于许多晶体物质中，所谓的含水成分包括构成地球的矿物和具有技术重要性的合成工业类似物。氢占地球的绝大多数，并且对地球内部的行为具有深远的影响，尽管氢在这些材料中具有明显的重要性，但含水成分可以显着改变合成材料的材料特性。在这种情况下，仍然存在两个基本的不确定性：1）氢在哪里融入晶体结构；2）氢的存在浓度如何。这项工作将通过实验室实验和计算机模拟的综合方法来解决这两个问题。除了继续研究先前研究的硅酸盐矿物（地球上最丰富的矿物）之外，该研究还将重点关注二元氧化物矿物。二进制氧化物不仅与地质相关，而且在许多成熟和新兴技术中也具有极大的相关性，从太阳能电池到激光、触摸屏、颜料、半导体和平板显示器，氢杂质已被证明在其中发挥着关键作用。因此，这项研究不仅对于了解地球的内部运作很重要，而且对于新技术的开发也具有重要意义。长期以来，人们一直认为含水成分（OH-和H2O）名义上是无水的。矿物（NAM）在地球科学中具有重要意义。这些相包括丰富的地幔相，例如橄榄石、石榴石、辉石和尖木岩，很可能是地球上最大的氢储库。NAM 中的微量氢通常会产生巨大的影响。尽管氢在 NAM 中具有明显的重要性，但仍然存在两个基本问题。在过去的几十年里，人们尝试或使用了许多技术，包括核剖面分析和 SIMS 测量，但与测量 NAM 中痕量氢浓度相关的技术挑战已被证明难以克服。尽管在特定的 NAM（例如石榴石）中已经确定了一些缺陷位点，但在大多数阶段，我们对这些问题提出的解决方案是一种考虑已建立的和考虑到的整体方法。涌现的测量矿物中痕量氢的技术和量子力学（密度泛函理论）计算将通过定向晶体的红外光谱联系起来，这已被证明是 NAM 研究的基础。氧化物矿物，如金红石和辉石，这是一组在 NAM 的研究中通常代表性不足的相，但其研究可以极大地有益于整个领域，并为技术的发展带来额外的好处该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。