Journal Article

PUBDB-2025-03923

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Cr$^{3+}$ -Containing Carbonates and Cr$_2$O$_3$ - Pbcn at Extreme Conditions

Wang, Y. (Corresponding author) ; Bayarjargal, L. ; Bykov, M.Extern* ; Bykova, E.Extern* ; Spahr, D.Extern* ; Glazyrin, K.XFEL.EU*DESY* ; Milman, V. ; Winkler, B.Extern*

2025
American Chemical Society Washington, DC

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Please use a persistent id in citations: doi:10.1021/acs.inorgchem.4c05003  doi:10.3204/PUBDB-2025-03923

Abstract: We synthesized three carbonates, Cr$_2$[CO$_3$]$_3$, Cr$_2$[C$_2$O$_5$][CO$_3$]$_2$, and Cr$_2$[CO$_3$][O]$_2$, containing Cr$^{3+}$ by laser heating of chromium oxides in CO$_2$ at pressures between 45 and 55 GPa. All phases were characterized by single-crystal X-ray diffraction and Raman spectroscopy, while density functional theory calculations complemented the experimental results. The structure of Cr$_2$[CO$_3$]$_3$-P6$_3$/m contains coplanar groups, and a 4f Wyckoff site is half occupied by Cr$^{3+}$. Cr$_2$[C$_2$O$_5$][CO$_3$]$_2$-C$_2$/c is characterized by coplanar [CO$_3$]$_2$− and pyro- [C$_2$O$_5$]$_2$− anions and is isostructural to Al$_2$[C$_2$O$_5$][CO$_3$]$_2$. It was obtained only after prolonged laser heating. The oxycarbonate Cr$_2$[CO$_3$][O]$_2$-Pbcn was synthesized at the highest pressure (55 GPa) studied here. In this structure, half of the oxygen atoms coordinate one carbon and two Cr atoms, while the other half coordinate three chromium atoms. The oxidation state of chromium in the carbonates is +3, independent of the oxidation state (+3 or +4) of chromium in the oxide starting material. We observed the transformation of Cr$_2$O$_3$-R3̅c to Cr$_2$O$_3$-Pbcn above 45(2) GPa after laser heating.

Note: We gratefully acknowledge funding from the DFG (projectsWI1232 and BA4020) and the DFG-Research Unit FOR2125/CarboPaT.

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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. DFG project G:(GEPRIS)264049573 - Carbonate und Schock-Kompression: Stabilität, Phasentransformation und chemische Reaktionen mit Silikaten (264049573) (264049573)
4. FS-Proposal: I-20231276 (I-20231276) (I-20231276)

Experiment(s):

1. PETRA Beamline P02.2 (PETRA III)

Appears in the scientific report 2025

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