Phase relations and physical properties of iron-oxygen compounds at multimegabar pressures and high temperatures

Fe-O系化合物的结构、性质和高温高压行为一直是人们研究的热点和难点。在过去的十年中，发现了几种化学计量未知的高压氧化铁。这些物质在地球科学（和行星科学）中作为地球吸积过程中的潜在相，作为现今地幔的可能成分，以及控制地幔、核-幔边界和地核中的氧逸度都是非常重要的。此外，新型铁氧化物及其电子和磁性对于现代固体物理学、化学、材料科学，甚至在这个行业里氧化铁将在超过200 GPa的压力和高达3500 K的温度下合成，并在激光加热的金刚石对顶砧单元（DAC）中进行原位研究。采用一系列先进的补充技术：X射线衍射（XRD）、穆斯堡尔和拉曼光谱（以及适用时的X射线吸收光谱和电阻率测量）和理论计算。该项目的方法目标是将单晶衍射研究扩展到200 GPa以上。将特别关注FeO、Fe 3 O 4、Fe 2 O3、Fe 4 O 5、Fe 5 O 6、Fe 5 O 7、Fe 7 O 9和FeO 2的研究。该项目的最终目标是建立覆盖整个地幔和地核重要部分的Fe-O系压力-温度-组成（P-T-X）相图，分析压力-温度诱导的Fe-O化合物转变如何影响地球内部的地球化学过程，揭示不同铁氧化物的结构、化学键和性质之间的关系，并研究它们之间的相互作用。并阐明了控制过渡金属氧化物在极端条件下行为的晶体化学原理。

The structures, properties and high-pressure and high-temperature behavior of compounds in the Fe–O system remain controversial and full of surprises despite a long history of research. Over the last decade several high-pressure iron oxides with hitherto unknown stoichiometries were discovered. These materials are very important for the geosciences (and planetary sciences) as potential phases during the Earth’s accretion, as possible components of present day mantle, and for controlling oxygen fugacity in the mantle, core mantle boundary, and in the core. Moreover, novel iron oxides, their electronic and magnetic properties are of great interest for modern solid state physics, chemistry, material sciences, and even for in the industry (as elements in switching electronics and memories).Iron oxides will be synthesized at pressures over 200 GPa and temperatures up to 3500 K and studied in situ in laser-heated diamond anvil cells (DACs) employing a range of advanced complementary techniques: X-ray diffraction (XRD), Mössbauer and Raman spectroscopy (and when applicable X-ray absorption spectroscopy and electrical resistivity measurements) and theoretical calculations. Methodological aim of the project is to extend single-crystal diffraction studies to over 200 GPa. Particular attention will be paid on studies of FeO, Fe3O4, Fe2O3, Fe4O5, Fe5O6, Fe5O7, Fe7O9, and FeO2. The ultimate goals of the project are to construct pressure-temperature-composition (P–T–X) phase diagram of Fe–O system at conditions covering entire Earth mantle and significant part of the core; analyze how pressure-temperature induced transformations in Fe–O compounds may affect geochemical processes in the Earth’s interior; reveal relations between structure, chemical bonding, and properties of different iron oxides; and formulate crystal chemical principals governing behavior of transition metal oxides at extreme conditions.