| 项目编号: | 1644614
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| 项目名称: | In Situ X-ray Diffraction Study of Phase Transitions in Shock-Compressed Minerals |
| 作者: | Thomas Duffy
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| 承担单位: | Princeton University
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| 批准年: | 2017
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| 开始日期: | 2017-01-01
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| 结束日期: | 2019-12-31
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| 资助金额: | 164000
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| 资助来源: | US-NSF
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| 项目类别: | Continuing grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Earth Sciences
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| 英文关键词: | x-ray
; mineral
; impact event
; shock compression experiment
; earth
; x-rays
; diffraction pattern
; shocked mineral
; high-pressure
; high-energy synchrotron x-ray diffraction capability
; high-energy synchrotron x-rays
; incident x-rays
; high-speed
; x-ray window
; transmission x-ray geometry
; shocked single crystal mineral
; high-speed impact experiment
; static high-pressure experiment
; x-ray diffraction frame
; shocked sample
; laboratory shock-compression experiment
; high-pressure structure texture
; x-ray detector
; powder x-ray diffraction measurement
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| 英文摘要: | High pressures and temperatures deep within the Earth transform minerals found near the Earth's surface to denser crystalline structures. High density forms of some minerals are also found in trace amounts at the Earth's surface as a result of past meteorite impact events. By impacting minerals with high-speed projectiles in laboratory shock-compression experiments, minerals can be rapidly driven into the high pressure and high temperature conditions occurring deep within the Earth's interior. As such, shock compression experiments have played an important role in earth science for decades by providing insight into the mechanical and acoustic properties of high-pressure minerals. However, past shock compression experiments on minerals have not directly revealed the crystal structures formed during impact and interpretation of shock compression experiments has relied on comparison with results of static high-pressure experiments. In the present research, high-energy synchrotron x-rays will be used during high-speed impact experiments on minerals to directly examine how mineral structures evolve on nanosecond to microsecond timescales during an impact event. The findings will improve our understanding of minerals in the Earth's mantle and will also allow us to better understand the crystal structure modifications occurring in shocked minerals during meteorite impact events. This project will support the training of a graduate student and two undergraduates who will be trained on National synchrotron facilities.
This project will be performed at the Dynamic Compression Sector (DCS) at the Advanced Photon Source. The DCS combines a half-inch bore two-stage gas gun capable of launching projectiles with velocities up to 6 km/s with high-energy synchrotron x-ray diffraction capability. Representative minerals such as enstatite, rutile and olivine will be shock compressed via high-speed impact to stresses up to about 60 gigapascals, pressures corresponding to those occurring in large natural meteorite impact events. The velocity histories at the rear surface of the shocked samples will be measured using velocity interferometry; the velocity histories will be analyzed to determine the stress and density of the shocked minerals. Powder x-ray diffraction measurements will also be made on the mineral samples during the impact event using a transmission x-ray geometry in which the incident x-rays pass through the impactor (LiF or polycarbonate), the mineral sample and an x-ray window (LiF or polycarbonate). An x-ray detector will be used to obtain four x-ray diffraction frames (100 picoseconds duration snapshots separated in time by 153.4 nanoseconds) during the impact event. The resulting diffraction patterns will be used to identify the high-pressure mineral structures. Diffraction patterns for shocked single crystal minerals will also be analyzed to understand the high-pressure structure texture which will provide insight into the atomic motions occurring during the structural transformations. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/90695
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
Thomas Duffy. In Situ X-ray Diffraction Study of Phase Transitions in Shock-Compressed Minerals. 2017-01-01.
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