Changes in the molecular structure of iron ore in the Earth’s core could mean that Earth has a layer of liquid oxygen, with 10 times as much oxygen as the entire atmosphere.
A team of Russian and German geophysicists have discovered a new layer in the Earth’s core, which is believed to be composed of liquid oxygen. While oxygen generally remains a gas at high temperatures, its boiling point goes up in high pressure environments. Researchers made the discovery by putting samples of iron ore into a laser heating device in a high pressure chamber, which showed that the iron oxides believed to be in the Earth’s core decomposed, releasing oxygen.
“The amount of oxygen produced by the formation of Fe5O7 alone can be as high as 8-10 times the mass of oxygen in the actual atmosphere,” according to the article which was published based on the research.
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 Fe3O4observed 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. (nature.com)