Optical Study of Thermal conductivity of Deep Earth's Materials at High Pressure and Temperature

高温高压下地球深部材料热导率的光学研究

• 批准号: 1015239
• 负责人: Alexander Goncharov
• 金额: $ 27.27万
• 依托单位: Carnegie Institution of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1015239&HistoricalAwards=false
• 关键词: Optical; Study; Thermal; conductivity; Deep

Knowledge of thermal conductivity and thermal diffusivity of the Earth's minerals under extreme conditions is important for understanding the physical and chemical processes and their evolution in the Earth. The rate of the heat transport through the mantle is crucial for the existence and stability of the Earth's magnetic field. The temperature distribution inside the Earth's mantle depends on the rate of heat transfer by convection, conduction, and radiation. An understanding of these processes requires knowledge of the thermal conductivity as a function of pressure and temperature. In this project, we propose to determine the thermal conductivity of the Earth's key minerals under high P-T conditions by using optical spectroscopy in DACs (Diamond Anvil Cells) including pump-probe pulsed laser techniques. To determine the lattice thermal conductivity, we will measure the heat fluxes across the sample and their time history using time- and spatially resolved spectroradiometry and/or time-domain thermoreflectance (TDTR). Both continuous and pulsed laser techniques will be employed to access the thermal conductivity and diffusivity. To infer the radiative thermal conductivity, we will study the optical spectra of these mantle minerals in the ultraviolet-to-infrared spectral range at high P-T conditions (up to 130 GPa and 4000 K). Silicate perovskite and ferropericlase, the two dominant phases of the Earth's lower mantle, will be studied. Single crystals grown from pre-synthesized materials with a composition close to that in the Earth's mantle will be used as samples. We will also study the thermal conductivity of the postperovskite phase, synthesized by laser heating. To better understand the thermal transport and Earth's temperature profile near the Core-Mantle Boundary (CMB), we will measure the thermal conductivity of iron (using also electrical and optical conductivity methods). These experimental data will give a direct estimate of the radiative and conduction parts of the thermal conductivity, so they can be utilized in model calculations of the thermal processes in the Earth, thus providing a crucial test of these models and our current understanding of the Earth's interior. This work will advance discovery and understanding by including graduate and undergraduate students as participants in the proposed research. A range of students, including area high school students, undergraduates, graduate students, and postdoctoral associates, will benefit from the scientific training at Carnegie that will be provided by participation in cutting-edge science that will be developed in the course of this work. We have developed collaborations with US and foreign Universities that allow us to train and incorporate graduate student research into our project. Moreover, we broaden participation of under-represented groups by establishing collaborations with Universities serving such groups and by including women and foreign postdoctoral associates (using exchange programs) into the research. Our project enhances infrastructure for research and education through several fruitful collaborations with the US and foreign Universities. We offer the use of our Carnegie optical facilities for our collaborators (and also NSF-supported programs such as COMPRES and the Carnegie Summer Intern Program, as well as the DOE-supported CDAC high-pressure center, headquartered at Carnegie).

在极端条件下，地球矿物质的热导率和热扩散率的了解对于理解物理和化学过程及其在地球中的演变很重要。通过地幔的热传输速率对于地球磁场的存在和稳定性至关重要。地球内部内部的温度分布取决于对流，传导和辐射的传热速率。对这些过程的理解需要了解导热率作为压力和温度的函数。在该项目中，我们建议通过在高P-T条件下使用光谱法（钻石砧细胞）（包括泵浦探针脉冲激光技术）中的光谱来确定地球关键矿物质的热导率。为了确定晶格导热率，我们将使用时间和空间分辨的光谱法和/或时间域热率（TDTR）来测量样品及其时间历史的热通量及其时间历史。连续和脉冲激光技术都将用于接收导热率和扩散率。为了推断辐射导热率，我们将在高P-T条件下（高达130 GPA和4000 K）研究这些地幔矿物的光谱。将研究硅酸盐钙钛矿和铁磷酸盐酶，这是地球下地幔的两个主要阶段。从与地球地幔中的成分接近的合成材料生长的单晶体将用作样品。我们还将研究通过激光加热合成的postperovskite相的热导率。为了更好地理解核心壳边界（CMB）附近的热传输和地球温度曲线，我们将测量铁的导热率（也使用电导率和光导电方法）。这些实验数据将直接估算热导率的辐射和传导部分，因此可以在地球中热过程的模型计算中使用它们，从而对这些模型以及我们当前对地球内部的理解提供了重要的测试。 这项工作将通过将毕业生和本科生作为拟议研究的参与者包括在内，从而提高发现和理解。包括地区高中生，本科生，研究生和博士后同事在内的一系列学生将受益于卡内基的科学培训，这些培训将由参与尖端科学提供，这将在这项工作中开发。我们已经与我们和外国大学建立了合作，使我们能够培训并将研究生研究纳入我们的项目中。此外，我们通过与为这些群体服务的大学建立合作，包括妇女和外国博士后伙伴（使用交流计划）在研究中扩大了代表性不足的群体的参与。我们的项目通过与美国和外国大学的几次富有成果的合作来增强研究和教育的基础设施。我们为我们的合作者提供了卡内基光学设施（以及NSF支持的计划，例如Compres和Carnegie Summer Intern计划，以及DOE支持的CDAC高压中心，总部位于Carnegie）。