How do magnetic interactions in nanoscale intergrowths affect palaeomagnetic interpretations?

纳米级共生体中的磁相互作用如何影响古地磁解释？

• 批准号: NE/D002036/1
• 负责人: Wyn Williams
• 金额: $ 54.41万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FD002036%2F1
• 关键词: How; do; magnetic; interactions; nanoscale

We are all familiar with the experiment where we place a piece of paper on top of a bar magnet and image the magnetic field by sprinkling iron filings on to the paper. The iron filings align with the magnetic field of the magnet, tracing out the well-known dipole field pattern. In this type of experiment the magnetic particles are free to move toward the high field regions. If the particles had been glued to the paper so that they could not move, then the magnetisation within the particles would have moved instead. In fact the magnetisation within the particles would rotate to align with the direction field of the magnet, but of course this rotation would not have been visible to the eye. The ability of the magnetisation within a particle to align with a magnetic field and remain aligned even if we remove the original magnetising field, means the particles are able to produce a permanent record of the field direction. This recording capability of small magnetic particles has been exploited by man for over 50 years, and used, for example, in magnetic tape recorders and for hard drive computer storage. In both tapes and drives the recording media consists of a thin film coated with a fine power of magnetic particles. Such technology allows computer drives to store huge amounts of data which can be deleted and recorded time and time again, but this high reliability can only be achieved by ensuring that all the magnetic particles are of a consistent grain size and chemical purity. Magnetic particles are not just man-made, but also occur naturally in most rocks and soils. Unlike man-made recording media, however, these naturally occurring magnetic minerals can have a wide variety of chemical compositions, grain sizes, and particle concentrations. In some cases these magnetic minerals will contain zones within a single grain with each zone having a slightly different chemical structure. These distinct magnetic minerals will develop in response to environmental conditions at the time when the rocks or soils are formed. For example, lavas thrown out from the same volcano can produce different magnetic minerals depending on how slowly the lavas cool, and soils will contain different magnetic minerals depending on the amount of organic material present. Being able to correctly identify the type of magnetic mineralogy, therefore, can tell us something about the environment in which that sample was formed. Accurate identification of the magnetic minerals is important for another reason. Natural magnetic minerals will record the direction of the Earth's magnetic field as the minerals are formed. However, the reliability of the recording will greatly depend upon the types of magnetic minerals that are present. It is possible that the direction of magnetisation in some minerals is more influenced by the crystalline structure of the mineral itself rather than the geomagnetic field. This is thought to be likely in the case when a magnetic grain is chemically zoned, as mentioned earlier. It is therefore important to understand how different multi-zoned grains are able to make a magnetic recording, and develop simple tests to distinguish which mineral systems are reliable recorders of the geomagnetic field, and which are not.

我们都熟悉这样的实验，我们把一张纸放在条形磁铁的顶部，然后通过在纸上洒上铁屑来成像磁场。铁屑与磁铁的磁场对齐，描绘出众所周知的偶极磁场模式。在这种类型的实验中，磁性粒子可以自由地向高场区域移动。如果粒子被粘在纸上，所以它们不能移动，那么粒子内部的磁化作用就会移动。事实上，粒子内部的磁化作用会旋转，以与磁铁的方向磁场对齐，但当然，这种旋转是肉眼看不到的。粒子内的磁化作用能够与磁场对准并保持对准，即使我们移除原始的磁化磁场，这意味着粒子能够产生磁场方向的永久记录。这种小磁性颗粒的记录能力已经被人类开发了50多年，并用于例如磁带记录器和硬盘驱动器计算机存储。在磁带和驱动器中，记录介质都由一层涂有细微磁性颗粒的薄膜组成。这种技术允许计算机驱动器存储大量数据，这些数据可以一次又一次地删除和记录，但这种高可靠性只能通过确保所有磁性颗粒具有一致的颗粒大小和化学纯度才能实现。磁性颗粒不仅是人造的，而且在大多数岩石和土壤中也是自然存在的。然而，与人造记录介质不同的是，这些自然产生的磁性矿物可以具有各种各样的化学成分、颗粒大小和颗粒浓度。在某些情况下，这些磁性矿物将包含单个颗粒内的区域，每个区域的化学结构略有不同。当岩石或土壤形成时，这些独特的磁性矿物会随着环境条件的变化而发展。例如，从同一座火山喷出的熔岩可以产生不同的磁性矿物，这取决于熔岩冷却的速度，土壤中含有不同的磁性矿物，这取决于存在的有机物质的数量。因此，能够正确识别磁性矿物学的类型可以告诉我们一些关于样品形成环境的信息。准确识别磁性矿物还有另一个重要原因。天然磁性矿物将在矿物形成时记录地球磁场的方向。然而，记录的可靠性将在很大程度上取决于存在的磁性矿物的类型。某些矿物的磁化方向可能更多地受矿物本身的晶体结构影响，而不是受地磁场的影响。如前所述，当磁性颗粒被化学分区时，这被认为是可能的。因此，重要的是要了解不同的多带颗粒如何能够进行磁记录，并开发简单的测试来区分哪些矿物系统是可靠的地磁场记录器，哪些不是。

项目成果

Magnetic properties of ilmenite-hematite single crystals from the Ecstall pluton near Prince Rupert, British Columbia MAGNETIC PROPERTIES OF ILMENITE-HEMATITE

不列颠哥伦比亚省鲁珀特王子港附近 Ecstall 岩体中钛铁矿-赤铁矿单晶的磁性 钛铁矿-赤铁矿的磁性

• DOI: 10.1029/2011gc003622
• 发表时间: 2011
• 期刊: Geochemistry, Geophysics, Geosystems
• 作者: Brownlee S

The application of Lorentz transmission electron microscopy to the study of lamellar magnetism in hematite-ilmenite

• DOI: 10.2138/am.2009.2989
• 发表时间: 2009-02
• 期刊: American Mineralogist
• 影响因子: 3.1
• 作者: T. Kasama;R. Dunin‐Borkowski;T. Asaka;R. Harrison;R. Chong;S. McEnroe;E. Simpson;Y. Matsui;A. Putnis

Visualized Effects of Oxidation and Temperature on Vortex-State Fe3O4 Particles Examined by Environmental TEM and Off-Axis Electron Holography

通过环境 TEM 和离轴电子全息术检查氧化和温度对涡旋态 Fe3O4 颗粒的可视化影响

• DOI: 10.1017/s143192761800524x
• 发表时间: 2018
• 期刊: Microscopy and Microanalysis
• 影响因子: 2.8
• 作者: Almeida T

Magnetic and microscopic characterization of magnetite nanoparticles adhered to clay surfaces

• DOI: 10.2138/am.2009.3167
• 发表时间: 2009-08-01
• 期刊: AMERICAN MINERALOGIST
• 影响因子: 3.1
• 作者: Galindo-Gonzalez, Cecilia;Feinberg, Joshua M.;Dunin-Borkowski, Rafal E.
• 通讯作者: Dunin-Borkowski, Rafal E.

Ferrimagnetic/ferroelastic domain interactions in magnetite below the Verwey transition. Part I: electron holography and Lorentz microscopy

• DOI: 10.1080/01411594.2012.695373
• 发表时间: 2013-01-01
• 期刊: PHASE TRANSITIONS
• 影响因子: 1.6
• 作者: Kasama, Takeshi;Harrison, Richard J.;Dunin-Borkowski, Rafal E.
• 通讯作者: Dunin-Borkowski, Rafal E.