Perovskite and post-perovskite in the (Mg,Fe)GeO3 system

(Mg,Fe)GeO3体系中的钙钛矿和后钙钛矿

• 批准号: 1415321
• 负责人: Thomas Duffy
• 金额: $ 36万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1415321&HistoricalAwards=false
• 关键词: Perovskite; post; perovskite; Mg; Fe

The geological activity at Earth's surface that can so profoundly affect humanity ultimately arises from on-going processes within the deep interior. These large-scale processes are in turn controlled by the properties of the constituent materials of the deep Earth. A mineral's crystal structure is its most fundamental characteristic, from which all other physical and chemical properties follow. Due to the incredibly high pressures (millions of atmospheres) and temperatures (thousands of degrees) of the deep Earth, our knowledge of the crystal structures of minerals residing near the base of Earth's mantle remains far from complete. This region of the Earth is primarily composed of silicate minerals that adopt structures known as perovskite and post perovskite. In this project, the PI will conduct laboratory experiments to probe the basic structural properties of magnesium iron germanates, a class of compounds that serve as close analogs for the silicate minerals of the deep Earth, but which can be studied at lower pressures and temperatures which are more easily attainable in the laboratory. Through this work, he and his team will provide fundamental knowledge of mineral crystal structures and properties that are needed to understand and interpret geophysical observations of the Earth's interior. The Earth's deep lower mantle is key for understanding the overall structure, dynamics, and evolution of the planet. Seismic evidence indicates this region exhibits considerable chemical heterogeneity as exemplified by features such as large low shear velocity provinces, ultra-low velocity zones, and the complexity of the core-mantle boundary region. The PI will conduct high-pressure X-ray experiments on Fe-bearing compositions in the (Mg,Fe)GeO3 system, an analog for the silicates of the deep mantle. The advantage of this system is that the perovskite to post-perovskite transition occurs at much lower pressure for germanates, allowing the team to avoid or reduce the experimental complications that plague silicate studies at ultrahigh pressures. They will use the laser-heated diamond anvil cell to carry out a series of synchrotron-based studies of the crystal structure, equation of state, electronic configuration, and local environment of iron in germanates with the perovskite and post-perovskite structures. The results will lead to a better understanding of how iron content affects mineralogical behavior in these phases and will directly impact the fields of seismology, petrology, geodynamics, geochemistry, and mineralogy.

地球表面的地质活性最终会影响人类的深刻影响，这是由于深层内部的持续过程而产生的。这些大规模的过程又受深地球组成材料的特性控制。 矿物质的晶体结构是其最基本的特征，从中所有其他物理和化学特性都从中。 由于深地球的压力极高（数百万个气氛）和温度（数千度），因此我们对居住在地球底部附近的矿物晶体结构的了解仍然远离完整。地球的这个区域主要由采用称为钙钛矿和钙钛矿后的结构的硅酸盐矿物组成。 在该项目中，PI将进行实验室实验，以探测德国镁镁的基本结构特性，这是一类化合物，这些化合物是深层硅酸盐矿物质的紧密类似物，但可以在较低的压力和温度下研究，这些化合物可以研究在实验室中更容易获得。通过这项工作，他和他的团队将提供有关矿物晶体结构和特性的基本知识，这些知识是理解和解释地球内部的地球物理观察结果所需的。地球深层地幔是理解地球的整体结构，动力学和演变的关键。地震证据表明，该区域表现出相当大的化学异质性，例如大型低剪切速度省，超低速度区以及核心掩体边界区域的复杂性。 PI将对（MG，FE）GEO3系统中的Fe-bearention组合物进行高压X射线实验，这是对深地幔硅酸盐的类似物。该系统的优点是，钙钛矿到植物后的过渡发生在德国人的压力下，使团队避免或减少了在超高压压力下遇到硅酸盐研究的实验并发症。他们将使用激光加热的钻石砧细胞进行一系列基于同步加速器的研究，对德国人的晶体结构，状态方程，电子构型和铁的局部环境，并具有钙钛矿和玻璃后晶岩结构。结果将更好地理解铁含量如何影响这些阶段的矿物学行为，并将直接影响地震学，岩石学，地球动力学，地球化学和矿物学领域。