极端条件下研究铁元素在下地幔物质中的状态

铁是在下地幔物质中的一种主量元素，它的物理化学行为(分配系数、氧化态、自旋转变等)影响着宿主的结构稳定性和电热力学传输性。因此，铁在下地幔物质中的状态是解决许多重要地球科学问题的“钥匙”。本项目采用同步辐射表征技术、常规实验室的现代仪器及理论模拟方法，开展极端条件下铁元素在下地幔物质中状态的研究，主要涉及内容有铁方镁矿中铁的局域结构、铁方镁矿的熔融曲线、含铁矿物中铁的自旋态、铁镁在钙钛矿和方镁矿的配分系数。通过本项目的研究，获得下地幔物质中铁元素状态的内在本质联系，应用微观尺度得到的信息，为下地幔物质的组成、状态及其演化建立相应的约束条件。优化高压X射线吸收谱、X射线发射谱和微束X射线衍射的测试条件，进一步完善和促进国内同步辐射高压谱学在地球科学中的应用。

Iron is one of the major elements in the lower mantle, whose physical and chemical properties (partition coefficient, oxidation state, spin transition etc) affect its host’s structural stability and thermodynamic transportation. Therefore, iron states in the materials of the lower mantle are the key issue in geoscience filed. In present proposal, we will investigate on iron states in the materials of the lower mantle at extreme conditions using synchrotron radiation technology, modern instruments in house and theoretical simulations. The contents in detail are: iron local structure in the ferropericlase, melting curve of the ferropericlase, iron spin states of iron-bearing minerals, and Fe-Mg partition coefficient between Mg-perovskite and ferropericlase at high pressures. In the research project, we expect to obtain the essential relationship of iron element states of the materials in the lower mantle, and apply micro-scale information into the discussion of the structure, the composition and the evolution of the lower mantle. We will also optimize the measurement conditions of high-pressure X-ray absorption spectroscopy, and X-ray emission spectroscopy and micro-beam X-ray diffraction, and further improve and promote the application of synchrotron radiation high-pressure spectroscopy in the geoscience filed.