第一原理電子状態計算によるδ-AlOOHの高圧相の探索

概要

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δ-AlOOH is a high pressure phase of α-AlOOH (diaspore) and γ-AlOOH (boehmite). This phase is experimentally recognized to be stable up to ∼140 GPa. Since the extraordinary stability of δ-AlOOH at high pressure, this phase is considered to be a possible carrier and reservoir of water into the deep mantle in the subducting cold slabs. We recently predicted hydrogen bond symmetrization in this phase taking place above ∼30 GPa using first principles method. Since only δ-AlOOH and phase D (MgSi2O6H2), which should have symmetric hydrogen bonds, have been reported to be stable above 30 GPa among known hydrous minerals, hydrogen bond symmetrization would serve as stabilizing the hydrous minerals under high pressure. Stability limit and further high-pressure phase evolution of these phases are therefore interesting in terms of crystallography. Since there are currently no study on this issue, here we have explored a further existence of high pressure transition of the symmetric hydrogen bond structure of δ-AlOOH theoretically.
日本鉱物科学会の論文