Crystal structures and P-T phase diagrams of SrC [Formula: see text] O [Formula: see text] and BaC [Formula: see text] O [Formula: see text]

Dinara N Sagatova; Pavel N Gavryushkin; Nursultan E Sagatov; Maksim V Banaev

doi:10.1002/jcc.27210

Crystal structures and P-T phase diagrams of SrC $_{2}$ O $_{5}$ and BaC $_{2}$ O $_{5}$

J Comput Chem. 2023 Dec 15;44(32):2453-2460. doi: 10.1002/jcc.27210. Epub 2023 Aug 23.

Authors

Dinara N Sagatova^{1

2}, Pavel N Gavryushkin^{1

2}, Nursultan E Sagatov^{1

2}, Maksim V Banaev^{1

2}

Affiliations

¹ Sobolev Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia.
² Department of Geology and Geophysics, Novosibirsk State University, Novosibirsk, Russia.

PMID: 37610074
DOI: 10.1002/jcc.27210

Abstract

In this study, we present the results of a search for new stable structures of SrC $_{2}$ O $_{5}$ and BaC $_{2}$ O $_{5}$ in the pressure range of 0-100 GPa based on the density functional theory and crystal structure prediction approaches. We have shown that the recently synthesized pyrocarbonate structure SrC $_{2}$ O $_{5}$ - $P 2_{1} / c$ is thermodynamically stable for both SrC $_{2}$ O $_{5}$ and BaC $_{2}$ O $_{5}$ . Thus, SrC $_{2}$ O $_{5}$ - $P 2_{1} / c$ is stable relative to decomposition reaction above 10 GPa, while the lower-pressure stability limit for BaC $_{2}$ O $_{5}$ - $P 2_{1} / c$ is 5 GPa, which is the lowest value for the formation of pyrocarbonates. For SrC $_{2}$ O $_{5}$ , the following polymorphic transitions were found with increasing pressure: $P 2_{1} / c \to F d d 2$ at 40 GPa and 1000 K, $F d d 2 \to C 2$ at 90 GPa and 1000 K. SrC $_{2}$ O $_{5}$ - $F d d 2$ and SrC $_{2}$ O $_{5}$ - $C 2$ are characterized by the framework and layered structures of [CO $_{4}$ ] $^{4 -}$ tetrahedra, respectively. For BaC $_{2}$ O $_{5}$ , with increasing pressure, decomposition of BaC $_{2}$ O $_{5}$ - $P 2_{1} / c$ into BaCO $_{3}$ and CO $_{2}$ is observed at 34 GPa without any polymorphic transitions.

Keywords: carbonates; crystal structure prediction; density functional theory; orthocarbonates; pyrocarbonates.

Grants and funding

22-23-00925/Russian Science Foundation