Journal Article

PUBDB-2026-02121

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Experimental Observation of a Calcium Silicon Double Carbonate

Botan-Neto, B. D. (Corresponding author) ; Santamaria-Perez, D. (Corresponding author)Extern*XFEL.EU* ; Bungarten, J.Extern* ; Bayarjargal, L. ; Winkler, B.Extern* ; Otero-de-la-Roza, A. ; Wang, B.XFEL.EU*DESY*

2026
Wiley-VCH Weinheim

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Please use a persistent id in citations: doi:10.1002/anie.202524999  doi:10.3204/PUBDB-2026-02121

Abstract: Reactions between carbon dioxide (CO2) and silica (SiO2), as well as between carbonates and silicates, are central to understanding carbon behavior in planetary interiors and have important technological implications. Yet, only a few oxides are known in which carbon and silicon coexist within the same crystal lattice. These silicate–carbonates typically contain trigonal carbonate [CO3] groups and tetrahedrally coordinated silicate [SiO4] units. In the CaO–SiO2–CO2 system, no phase had previously been shown to contain both octahedrally coordinated silicon [SiO6] and carbonate [CO3] groups, nor had such a structure been theoretically predicted. Here, we report the synthesis of the calcium silicon double carbonate Ca2Si(CO3)4, obtained by reacting tilleyite, Ca5(Si2O7)(CO3)2, with CO2 in diamond anvil cells at 39.5 GPa and 2600 K. The compound was subsequently temperature- and pressure-quenched, remaining metastable at ambient conditions. Structural and spectroscopic characterization was performed using synchrotron single-crystal X-ray diffraction and Raman spectroscopy. The structure of Ca2Si(CO3)4 is unique among silicate–carbonates, featuring sixfold-coordinated Si sharing oxygen atoms with [CO3] groups. Additionally, a novel calcium tetracarbonate, Ca2(C4O10), containing tetrahedral [CO4] units, was discovered. These findings reveal a new oxide chemistry under extreme conditions and open avenues for synthesizing metastable carbon-bearing materials relevant to the deep carbon cycle.

Note: Deutsche Forschungsgemeinschaft (DFG, projects WI1232 and BA4020).

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)
2. PETRA-D (FS-PETRA-D)

Research Program(s):

1. 631 - Matter – Dynamics, Mechanisms and Control (POF4-631) (POF4-631)
2. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
3. FS-Proposal: I-20250095 EC (I-20250095-EC) (I-20250095-EC)

Experiment(s):

1. PETRA Beamline P02.2 (PETRA III)

Appears in the scientific report 2026

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Database coverage:
; ; ; Chemical Reactions ; Clarivate Analytics Master Journal List ; Current Contents - Life Sciences ; Current Contents - Physical, Chemical and Earth Sciences ; DEAL Wiley ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 15 ; Index Chemicus ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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