Abstract
We have predicted a high-pressure hydrous phase of AlOOH stabilizing at ∼170 GPa by first-principles density-functional calculations. The structure predicted has a cubic pyrite-type framework with interstitial H atoms forming symmetric hydrogen bonds, whose symmetry is assigned to the space group (No. 205). The predicted δ-AlOOH to the pyrite-type phase sequence is analogous to a recent theoretical and experimental discovery of high-pressure phase evolution in InOOH and invokes the high-pressure phase relationship in , but the transition pressure is much greater in AlOOH than in InOOH. Relative enthalpies also indicate that the dissociation of this phase into a -type phase of plus ice finally occurs at a further pressure of 300 GPa. The present results suggest that AlOOH has an unexpectedly wide stability range in pressure compared to common hydrous materials.
- Received 28 September 2010
DOI:https://doi.org/10.1103/PhysRevB.83.054115
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