Theoretical and Experimental Crystal Chemistry

理论与实验晶体化学

• 批准号: RGPIN-2015-04162
• 负责人: Hawthorne, Frank
• 金额: $ 3.64万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=653252
• 关键词: Theoretical; Experimental; Crystal; Chemistry

Minerals are the fundamental materials of the Earth, and if we wish to understand the processes which formed the Earth, and which continue to modify its landscape and the human environment, we need to understand the behaviour of minerals under the full spectrum of conditions experienced on Earth. This proposal focuses on a wide variety of minerals in an attempt to understand the atomic-scale factors affecting their constitution and behaviour, and to use this understanding to rationalize and predict their behaviour at the macroscopic scale. I use various forms of radiation (X-rays, neutrons) to 'see' into a mineral at the atomic scale via diffraction, and to derive the arrangement of atoms from which it is built. Details concerning atomic-scale disorder can be seen with spectroscopy using other forms of radiation (e.g. infrared, gamma rays). The resulting atomic-scale details of the mineral give us the information from which we can, in principle, understand aspects of how and at what conditions the mineral formed, and under what conditions it is stable. Why do minerals have the chemical formulae that they do? Why do they have their specific structural arrangements? Why are minerals stable over specific ranges of pH, Eh, temperature, pressure and constituent activities? What are the relations between crystal structure and enthalpy, entropy and Gibbs free energy of formation? How can we derive the atomic-scale mechanisms of geological processes? What is the relation of mathematical complexity to mineral structures and the behaviour of minerals in equilibrium and non-equilibrium processes? These questions are fundamental to Mineralogy itself and yet have tended to be ignored in the past because they are not susceptible to established theoretical techniques in Physics and Chemistry. A major part of this proposal involves the development of a theoretical approach to answer these questions, an approach based on the topology (connectivity) of chemical bonds in space. I will use various aspects of Mathematics (Graph Theory, Combinatorial Topology, Complexity Theory), Physics (Bond-Valence Theory) and Chemistry (the moments approach to the energy density-of-states of solids) to develop connections between patterns of bond connectivity (bond topology) and their energetic content, how these connections dictate the chemical compositions and structural connectivities of minerals, and the ways in which these factors affect how minerals participate in geological processes. This theoretical work is supported by an extensive experimental program of mineral characterization involving amphiboles and tourmalines, a new thrust on gem minerals, TS-block minerals, new minerals, and other diverse projects that can benefit from our local experimental capabilities and theoretical expertise.**

矿物是地球的基本材料，如果我们希望了解形成地球的过程，并继续改变地球的景观和人类环境，我们需要了解矿物在地球经历的全方位条件下的行为。地球。该提案重点关注各种矿物，试图了解影响其构成和行为的原子尺度因素，并利用这种理解在宏观尺度上合理化和预测它们的行为。辐射（X射线、中子）通过衍射在原子尺度上“观察”矿物，并推导出构成矿物的原子排列，有关原子尺度无序的细节可以通过使用其他形式的光谱学来观察。由此产生的矿物原子级细节为我们提供了原则上可以了解矿物如何以及在什么条件下形成的信息。为什么矿物质具有其特定的结构排列？为什么矿物质在特定的 pH、Eh、温度、压力和成分活性范围内保持稳定？晶体结构与形成的焓、熵和吉布斯自由能之间的关系是什么？我们如何推导出地质过程的原子尺度机制？数学复杂性与矿物结构和矿物行为之间的关系是什么？平衡和非平衡过程？这些问题是矿物学本身的基础，但在过去往往被忽视，因为它们不易受物理和化学中已建立的理论技术的影响。该提案的主要部分涉及理论的发展。回答这些问题的方法是基于空间化学键的拓扑（连通性）的方法，我将使用数学的各个方面（图论、组合拓扑、复杂性）。理论）、物理学（键价理论）和化学（固体能量态密度的矩方法），以建立键连接模式（键拓扑）与其能量含量之间的联系，这些联系如何决定化学矿物的成分和结构连通性，以及这些因素如何影响矿物参与地质过程的方式，这项理论工作得到了涉及角闪石和电气石的广泛矿物表征实验计划的支持，这是一个新的推动力。宝石矿物、TS-block 矿物、新矿物和其他可以受益于我们当地实验能力和理论专业知识的多样化项目。**