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P−T phase diagram of Na2C2O5 at pressures up to 100 GPa. / Sagatova, Dinara N.; Sagatov, Nursultan E.; Banaev, Maksim V. et al.
In: Solid State Communications, Vol. 397, 115764, 01.03.2025.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - P−T phase diagram of Na2C2O5 at pressures up to 100 GPa
AU - Sagatova, Dinara N.
AU - Sagatov, Nursultan E.
AU - Banaev, Maksim V.
AU - Gavryushkin, Pavel N.
N1 - Сведения о финансировании Финансирующий спонсор Номер финансирования Акроним Russian Science Foundation 23-73-10114 RSF
PY - 2025/3/1
Y1 - 2025/3/1
N2 - In this work, a detailed search for stable structures of the Na2C2O5 composition was carried out using first-principles calculations and modern crystal structure prediction approaches. It was found that the Na2C2O5 compound is formed as a result of the reaction Na2CO3 + CO2 at a pressure of 4.5 GPa at 0 K and is stable in the P21 structure. This structure is consistent with recent experiments on the synthesis of Na2C2O5. The structure of Na2C2O5-P21 belongs to a new class of compounds, namely pyrocarbonates, and is characterized by the presence of [C2O5] pyro-groups formed by [CO3] triangles bonded through a common oxygen atom. Unlike alkaline earth metals, stable structures characterized by the presence of [CO4] tetrahedra have not been found for Na2C2O5. The calculated P–T phase diagram indicates the stability of Na-pyrocarbonate relative to the decomposition reaction in the pressure range 4.5–52.7 GPa at 0 K (6–58.2 GPa at 1000 K). Thus, for the first time, the lower limit of stability of Na-pyrocarbonate has been determined, which at 0 K is the same as that of the recently discovered Li-pyrocarbonate. Calculations of the phonon spectrum indicate that Na-pyrocarbonate is dynamically stable at atmospheric pressure.
AB - In this work, a detailed search for stable structures of the Na2C2O5 composition was carried out using first-principles calculations and modern crystal structure prediction approaches. It was found that the Na2C2O5 compound is formed as a result of the reaction Na2CO3 + CO2 at a pressure of 4.5 GPa at 0 K and is stable in the P21 structure. This structure is consistent with recent experiments on the synthesis of Na2C2O5. The structure of Na2C2O5-P21 belongs to a new class of compounds, namely pyrocarbonates, and is characterized by the presence of [C2O5] pyro-groups formed by [CO3] triangles bonded through a common oxygen atom. Unlike alkaline earth metals, stable structures characterized by the presence of [CO4] tetrahedra have not been found for Na2C2O5. The calculated P–T phase diagram indicates the stability of Na-pyrocarbonate relative to the decomposition reaction in the pressure range 4.5–52.7 GPa at 0 K (6–58.2 GPa at 1000 K). Thus, for the first time, the lower limit of stability of Na-pyrocarbonate has been determined, which at 0 K is the same as that of the recently discovered Li-pyrocarbonate. Calculations of the phonon spectrum indicate that Na-pyrocarbonate is dynamically stable at atmospheric pressure.
KW - Alkali carbonates
KW - Carbonates
KW - Crystal structure prediction
KW - Density functional theory
KW - High pressures
KW - Phase diagrams
KW - Pyrocarbonates
UR - https://www.mendeley.com/catalogue/d695ec51-f8f0-3004-8abc-ed70e7443b01/
UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85211022064&origin=inward&txGid=eea479e6beda65a4ad72ef24d720834b
U2 - 10.1016/j.ssc.2024.115764
DO - 10.1016/j.ssc.2024.115764
M3 - Article
VL - 397
JO - Solid State Communications
JF - Solid State Communications
SN - 0038-1098
M1 - 115764
ER -
ID: 62800388