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

地球表面的地质活动能够如此深刻地影响人类，最终来自于地球内部深处正在进行的过程。这些大规模的过程反过来又受到地球深处组成物质的性质的控制。矿物的晶体结构是其最基本的特征，所有其他物理和化学性质都是由此而来的。由于地球深处令人难以置信的高压(数百万大气层)和温度(数千度)，我们对地幔底部附近矿物晶体结构的了解仍然很不完整。地球的这一区域主要由硅酸盐矿物组成，这些矿物采用了被称为钙钛矿和后钙钛矿的结构。在这个项目中，PI将进行实验室实验，以探索镁铁锗酸盐的基本结构特性，这是一种与地球深处的硅酸盐矿物非常相似的化合物，但可以在较低的压力和温度下进行研究，这在实验室更容易获得。通过这项工作，他和他的团队将提供矿物晶体结构和性质的基本知识，这些知识是理解和解释地球内部的地球物理观测所需的。地球深部的下地幔是了解地球整体结构、动力学和演化的关键。地震证据表明，该地区具有相当大的化学非均质性，表现为大的低剪切速度区、超低速带和核幔交界区的复杂性。PI将对(Mg，Fe)GeO_3系统中的含铁成分进行高压X射线实验，该系统类似于地幔深处的硅酸盐。这个系统的优点是，钙钛矿到后钙钛矿的转变发生在锗的压力低得多的情况下，使该团队能够避免或减少在超高压下困扰硅酸盐研究的实验并发症。他们将使用激光加热的钻石压腔对钙钛矿和后钙钛矿结构的锗中铁的晶体结构、状态方程、电子构型和局部环境进行一系列基于同步加速器的研究。这些结果将有助于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、地球化学和矿物学等领域。

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.