Silicon carbonate phase formed from carbon dioxide and silica under pressure

• Published in: Proceedings of the National Academy of Sciences - PNAS 2011-05, Vol.108 (19), p.7689-7692
• Main Authors: Santoro, Mario, Gorelli, Federico, Haines, Julien, Cambon, Olivier, Levelut, Claire, Garbarino, Gaston
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Carbonates; Chemical reactions; Chemical synthesis; chemistry; Condensed Matter; Diffraction; Disordered Systems and Neural Networks; High pressure; Infrared radiation; infrared spectroscopy; Materials; Metal oxides; Micropores; Oxides; Physical Sciences; Physics; porous media; Pressure; Silica; Silicon; Spectrum analysis; temperature; Thermodynamics; X-ray diffraction; zeolites
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1019691108

The discovery of nonmolecular carbon dioxide under high-pressure conditions shows that there are remarkable analogies between this important substance and other group IV oxides. A natural and long-standing question is whether compounds between CO₂ and SiO₂ are possible. Under ambient conditions, CO₂ and SiO₂ are thermodynamically stable and do not react with each other. We show that reactions occur at high pressures indicating that silica can behave in a manner similar to ionic metal oxides that form carbonates at room pressure. A silicon carbonate phase was synthesized by reacting silicalite, a microporous SiO₂ zeolite, and molecular CO₂ that fills the pores, in diamond anvil cells at 18-26 GPa and 600-980 K; the compound was then temperature quenched. The material was characterized by Raman and IR spectroscopy, and synchrotron X-ray diffraction. The experiments reveal unique oxide chemistry at high pressures and the potential for synthesis of a class of previously uncharacterized materials. There are also potential implications for CO₂ segregation in planetary interiors and for CO₂ storage.