Theoretical and Experimental Crystal Chemistry

矿物是地球的基本物质，如果我们想要了解形成地球并继续改变其景观和人类环境的各种过程，我们需要了解矿物在地球上经历的各种条件下的行为。这项建议侧重于研究种类繁多的矿物，试图了解影响其构成和行为的原子尺度因素，并利用这一理解在宏观尺度上对其行为进行合理解释和预测。我使用各种不同形式的辐射(X射线、中子)，通过衍射在原子尺度上看到一种矿物，并推导出构成它的原子的排列。有关原子尺度无序的细节可以通过使用其他形式的辐射(例如红外线、伽马射线)的光谱学来查看。由此产生的原子尺度的矿物细节为我们提供了信息，原则上我们可以从中了解矿物是如何形成的，在什么条件下形成，以及在什么条件下是稳定的。为什么矿物会有它们所拥有的化学式？为什么他们会有自己的具体结构安排？为什么矿物在特定的pH、Eh、温度、压力和组分活动范围内是稳定的？晶体结构与焓、熵、吉布斯自由生成能有什么关系？我们如何才能得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在平衡和非平衡过程中的行为特征之间的关系是什么？这些问题对矿物学本身来说是非常基本的，但在过去往往被忽视，因为它们不容易受到物理学和化学中既定理论技术的影响。这项提议的一个重要部分涉及开发一种理论方法来回答这些问题，一种基于空间中化学键的拓扑(连通性)的方法。我将使用数学(图论、组合拓扑学、复杂性理论)、物理学(键价理论)和化学(接近固体能量密度的矩)的各个方面来建立键和连接性模式(键拓扑)与它们的能量含量之间的联系，这些联系如何决定矿物的化学成分和结构连接性，以及这些因素如何影响矿物参与地质过程。这项理论工作得到了一项广泛的矿物表征实验计划的支持，该计划涉及角闪石和电气石、宝石矿物、TS块状矿物、新矿物以及其他可以受益于我们当地的实验能力和理论专业知识的不同项目。

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.