Bayarjargal Lkhamsuren, Spahr Dominik, Milman Victor, Marquardt Julien, Giordano Nico, Winkler Björn
Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, Frankfurt 60438, Germany.
Dassault Systèmes BIOVIA, 334 Cambridge Science Park, Cambridge CB4 0WN, U.K.
Inorg Chem. 2023 Aug 28;62(34):13910-13918. doi: 10.1021/acs.inorgchem.3c01832. Epub 2023 Aug 14.
We synthesized the inorganic anhydrous aluminum carbonates Al[CO][CO] and Al[CO] by reacting AlO with CO at high pressures and temperatures and characterized them by Raman spectroscopy. Their structures were solved by X-ray diffraction. Al[CO] forms at around 24-28 GPa, while Al[CO][CO] forms above 38(3) GPa. The distinguishing feature of the new Al[CO][CO]-structure type is the presence of pyrocarbonate [CO]-groups, trigonal [CO]groups, and octahedrally coordinated trivalent cations. Al[CO] has isolated [CO]-groups. Both Al-carbonates can be recovered under ambient conditions. Density functional theory calculations predict that CO will react with FeO, TiO, GaO, InO, and MgSiO at high pressures to form compounds which are isostructural to Al[CO][CO]. MgSi[CO][CO] is predicted to be stable at pressures relative to abundant mantle minerals in the presence of CO. This structure type allows the incorporation of four elements (Mg, Si, Fe, and Al) abundant in the Earth's mantle in octahedral coordination and provides an alternative phase with novel carbon speciation for carbon storage in the deep Earth.
我们通过在高压和高温下使Al₂O₃与CO反应合成了无机无水碳酸铝Al[CO₃]和Al[CO₃]₂，并通过拉曼光谱对其进行了表征。它们的结构通过X射线衍射确定。Al[CO₃]在约24 - 28 GPa时形成，而Al[CO₃]₂在38(3) GPa以上形成。新型Al[CO₃]₂结构类型的显著特征是存在焦碳酸盐[CO₃]²⁻基团、三角[CO₃]³⁻基团和八面体配位的三价阳离子。Al[CO₃]具有孤立的[CO₃]²⁻基团。两种碳酸铝在环境条件下都可以回收。密度泛函理论计算预测，在高压下CO将与FeO、TiO₂、Ga₂O₃、In₂O₃和MgSiO₃反应形成与Al[CO₃]₂同结构的化合物。预计在有CO存在的情况下，相对于丰富的地幔矿物，MgSi[CO₃]₂在压力下是稳定的。这种结构类型允许将在地幔中丰富的四种元素（Mg、Si、Fe和Al）以八面体配位形式纳入，并为地球深部的碳储存提供了一种具有新型碳形态的替代相。
