Acquisition of high-temperature rock-magnetic instruments

获取高温岩磁仪器

• 批准号: 1261772
• 负责人: Bruce Moskowitz
• 金额: $ 33.41万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1261772&HistoricalAwards=false
• 关键词: Acquisition; temperature; rock; magnetic; instruments

The project will expand experimental capabilities at the Institute for Rock Magnetism (IRM) through the acquisition of two new instruments:The first is a Asylum Research MFP-3D Magnetic Force Microscope. This instrument maps the spatial distribution of magnetic field gradients at a controlled height above the surface of a magnetic material sample, with a resolution of a few tens of nanometers, over areas up to ~100 micrometers, thereby allowing observation of the micromagnetic structure of the material (domains and domain walls). In addition to room-temperature imaging, the MFP-3D also allows high-temperature imaging up to 400°C. This is accomplished with a separate high temperature environmental stage (PolyHeater) that sits on the MFP-3D XY scanning stage. Heating and cooling can be done in air or controlled atmospheres (e.g., He, Ar, CO, etc). Sample temperature can be maintained to better than 0.2°C precision with accuracy to 0.5°C and temperature overshoots less than 0.2°C. All control and measurement functions are fully programmable for custom heating-cooling imaging experiments. The second is an AGICO MFK1-FA Kappabridge and CS4 Furnace. This instrument measures both ?real? (in-phase) and ?imaginary? (quadrature) components of complex susceptibility, with three AC operating frequencies (976, 3904 and 15616 Hz) and a range of applied AC field intensities from 2 A/m up to a maximum of 700 A/m (depending on frequency). High spatial uniformity of both applied fields and the instrument response function allow accurate measurement of the magnetic anisotropy of geological samples having various sizes and shapes, and an integrated specimen rotator in the MFK1-FA enables rapid automated acquisition of orientation-dependent data. The CS4 furnace, integrated with the MFK1-FA, will enable measurements of frequency- and amplitude-dependent susceptibility at elevated temperature, which will be important new capabilities. The new high-temperature capabilities of these two instruments will allow resident and visiting researchers at the Institute for Rock Magnetism to probe the fundamental physical origins of magnetic ?memory? in geologically significant magnetic materials such as magnetite, titanomagnetite, hematite, hemoilmenite, and pyrrhotite. The nonuniform magnetizations in micrometer-to-millimeter sized particles of these minerals provide us with the paleomagnetic ?recordings? of past geomagnetic field strength and orientation that allow us to study the evolution of the earth?s deep interior, the motion of tectonic plates, and other significant problems in the geosciences, biosciences, planetary geology, and meteoritic studies. Observation of the micromagnetic configurations within mineral grains, and their changes with experimentally applied fields and controlled temperatures, allows us to study the mechanisms of natural magnetic recording, to understand their sensitivity to thermal or chemical overprinting over geologic time, and to devise optimized laboratory methods for the recovery of paleomagnetic field data from natural recording media.

该项目将通过购买两台新仪器来扩展岩石磁学研究所 (IRM) 的实验能力：第一个是 Asylum Research MFP-3D 磁力显微镜，该仪器可绘制受控高度处磁场梯度的空间分布。磁性材料样品表面上方的分辨率为几十纳米，区域可达约 100 微米，从而可以观察材料的微磁结构（磁畴和磁畴壁）。除了室温成像之外，MFP-3D 还允许高达 400°C 的高温成像，这是通过位于 MFP-3D XY 扫描台上的独立高温环境台 (PolyHeater) 来实现的。在空气或受控气氛（例如 He、Ar、CO 等）中进行，样品温度可保持在 0.2°C 以上的精度，精度可达 0.5°C，并且温度超调。低于 0.2°C。第二个是 AGICO MFK1-FA Kappabridge 和 CS4 炉，可测量“真实”（同相）和“虚拟”。复杂磁化率的（正交）分量，具有三个交流工作频率（976、3904 和 15616 Hz）和一系列应用的交流场强度从 2 A/m 到最大 700 A/m（取决于频率），应用场和仪器响应函数的高空间均匀性可以精确测量具有各种尺寸和形状的地质样品的磁各向异性。 MFK1-FA 中的集成样品旋转器可快速自动采集与方向相关的数据。与 MFK1-FA 集成的 CS4 炉可在高温下测量与频率和振幅相关的磁化率。这两台仪器的新高温功能将使岩石磁学研究所的常驻和访问研究人员能够探索具有地质意义的磁性材料（例如磁铁矿、钛磁铁矿、赤铁矿、这些矿物的微米到毫米大小的颗粒的不均匀磁化为我们提供了过去的古地磁“记录”。地磁场强度和方向使我们能够研究地球内部深处的演化、构造板块的运动以及地球科学、生物科学、行星地质学和矿物内部微磁结构观测中的其他重大问题。颗粒及其随实验施加的场和受控温度的变化，使我们能够研究自然磁记录的机制，了解它们在地质时期对热或化学叠印的敏感性，并设计优化的方案从自然记录介质恢复古磁场数据的实验室方法。