Although chemically very simple, Fe2O3 is known to undergo a series of enigmatic structural, electronic and magnetic transformations at high pressures and high temperatures. So far, these transformations have neither been correctly described nor understood because of the lack of structural data. Here we report a systematic investigation of the behaviour of Fe2O3 at pressures over 100 GPa and temperatures above 2,500 K employing single crystal X-ray diffraction and synchrotron Mössbauer source spectroscopy. Crystal chemical analysis of structures presented here and known Fe(II, III) oxides shows their fundamental relationships and that they can be described by the homologous series nFeO·mFe2O3. Decomposition of Fe2O3 and Fe3O4 observed at pressures above 60 GPa and temperatures of 2,000 K leads to crystallization of unusual Fe5O7 and Fe25O32 phases with release of oxygen. Our findings suggest that mixed-valence iron oxides may play a significant role in oxygen cycling between earth reservoirs.

中文翻译：

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简单的Fe2O3在高压和高温下的结构复杂性。

尽管化学上非常简单，但已知Fe2O3在高压和高温下会经历一系列神秘的结构，电子和磁性转变。到目前为止，由于缺乏结构数据，因此尚未正确描述或理解这些转换。在这里，我们报告了使用单晶X射线衍射和同步加速器Mössbauer源光谱在100 GPa以上的压力和2500 K以上的温度下Fe2O3的行为的系统研究。此处介绍的结构和已知的Fe（II，III）氧化物的晶体化学分析显示出它们的基本关系，并且可以用同源系列nFeO·mFe2O3进行描述。在高于60 GPa的压力和2的温度下观察到Fe2O3和Fe3O4的分解，000 K会导致不寻常的Fe5O7和Fe25O32相结晶并释放出氧气。我们的发现表明，混合价铁氧化物可能在地球储层之间的氧气循环中起重要作用。