Simulations of dislocation-mediated deformation, attenuation and dispersion in the Earth's mantle

地幔中位错介导的变形、衰减和色散的模拟

• 批准号: NE/E012922/1
• 负责人: Andrew Walker
• 金额: $ 28.66万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FE012922%2F1
• 关键词: Simulations; dislocation; mediated; deformation; attenuation

Understanding the structure and behavior of the Earth requires both geophysical observation and studies of the properties of the materials which are believed to comprise the deep interior. Seismology is a particularly powerful way to observe the interior, but to extract the structure, temperature and composition of the mantle and core the elastic behavior of minerals must be known to extreme temperature and pressure, pushing the limits of experiment. To sidestep this problem much of the data now used is actually generated by computer simulation of minerals performed at the atomic scale and this approach has been phenomenally successful in recent years. However, these approaches have only considered the elastic response of the minerals - the fact that energy is dissipated as seismic waves pass through the Earth is ignored. A second related factor is also not provided by calculating the pure elastic response, the fact that seismic waves with different frequencies travel at different speeds. To understand these two effects, which are known as attenuation and dispersion, we must study anelasticity - the time delayed response to the passage of the seismic wave. Anelasticity is the result of the presence of imperfections or defects in the mineral structure. These imperfections are also the agents responsible for long term flow in the mantle, a process which results in plate tectonics, growth of mountain ranges, volcanism and many of the processes that make the Earth we see today. Key to the project is the ability to simulate crystals containing defects and especially a type of defect called dislocations. By studying dislocations on the atomic scale the project will allow seismologists to extract more information from the observed data and will enhance our understanding of the Earth's interior. With a solid understanding of the causes of attenuation and dispersion it will be possible to extract much more information about the nature of the Earth's interior from observation. The research will also be valuable in other fields where dislocations alter the properties of materials. For example, the problem of deformation of pharmaceuticals during the production of tablets could be addressed by the methods developed for the study of the Earth's interior. Furthermore dislocations in materials used in computer chips, catalysts, fuel cells and batteries alter the behavior of these materials and the methods can be used to tackle all these problems. Finally, dislocation emerging at the surface of crystals allow reactions to take place on the surface, one example of an environment where this could be important is the interaction between pollutants and ices in clouds in the the upper atmosphere.

了解地球的结构和行为需要地球物理观察和对材料的性质的研究，这些材料的性质被认为包括深层内部。地震学是一种观察内部的特别有力的方法，但是要提取地幔和核心的结构，温度和组成，必须知道矿物的弹性行为，以极高的温度和压力，从而突出实验的范围。为了避开这个问题，现在所使用的许多数据实际上是通过在原子量表上进行的矿物进行的计算机模拟而生成的，近年来，这种方法取得了惊人的成功。但是，这些方法仅考虑了矿物质的弹性反应 - 当地震波穿过地球时，能量被消散。还不能通过计算纯弹性响应来提供第二个相关因素，即具有不同频率的地震波以不同的速度传播的事实。要理解这两种效应，称为衰减和分散，我们必须研究无弹性 - 对地震波通过的时间延迟响应。厌氧性是矿物结构中缺陷或缺陷的结果。这些缺陷也是负责地幔长期流动的代理，这一过程导致板块构造，山脉的生长，火山和许多使我们今天看到的地球的过程。该项目的关键是能够模拟包含缺陷的晶体，尤其是一种称为脱位的缺陷。通过在原子量表上研究位错，该项目将使地震学家从观察到的数据中提取更多信息，并增强我们对地球内部的理解。通过对衰减和分散的原因有着深入的了解，可以从观察中提取有关地球内部性质的更多信息。这项研究在其他领域的其他领域也将很有价值，这些领域改变了材料的性质。例如，可以通过为地球内部研究开发的方法来解决药品生产过程中药品变形的问题。此外，计算机芯片，催化剂，燃料电池和电池中使用的材料中的位错改变了这些材料的行为，可以使用这些方法来解决所有这些问题。最后，在晶体表面出现的脱位使反应在表面上发生，这可能很重要的环境的一个例子是污染物与高层大气中的云层之间的相互作用。

项目成果

The compressibility and high pressure structure of diopside from first principles simulation

• DOI: 10.1007/s00269-008-0229-3
• 发表时间: 2008-03
• 期刊: Physics and Chemistry of Minerals
• 影响因子: 1.4
• 作者: A. Walker;Rick Tyer;R. Bruin;M. Dove

A computational study of order-disorder phenomena in Mg2TiO4 spinel (qandilite)

• DOI: 10.2138/am.2008.2896
• 发表时间: 2008-08
• 期刊: American Mineralogist
• 影响因子: 3.1
• 作者: E. Palin;A. Walker;R. Harrison