Temperature-induced amorphization in CaCO3 at high pressure and implications for recycled CaCO3 in subduction zones
Open Access
- 29 April 2019
- journal article
- research article
- Published by Springer Science and Business Media LLC in Nature Communications
- Vol. 10 (1), 1963
- https://doi.org/10.1038/s41467-019-09742-5
Abstract
Calcium carbonate (CaCO3) significantly affects the properties of upper mantle and plays a key role in deep carbon recycling. However, its phase relations above 3 GPa and 1000 K are controversial. Here we report a reversible temperature-induced aragonite-amorphization transition in CaCO3 at 3.9–7.5 GPa and temperature above 1000 K. Amorphous CaCO3 shares a similar structure as liquid CaCO3 but with much larger C-O and Ca-Ca bond lengths, indicating a lower density and a mechanism of lattice collapse for the temperature-induced amorphous phase. The less dense amorphous phase compared with the liquid provides an explanation for the observed CaCO3 melting curve overturn at about 6 GPa. Amorphous CaCO3 is stable at subduction zone conditions and could aid the recycling of carbon to the surface.Keywords
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