TY - JOUR

T1 - First-Principles investigation of Pressure-Induced structural transformations of barium borates in the BaO-B2O3-BaF2 system in the range of 0–10 GPa

AU - Sagatov, Nursultan E.

AU - Bekker, Tatyana B.

AU - Podborodnikov, Ivan V.

AU - Litasov, Konstantin D.

N1 - Funding Information: We thank the Information and Computing Center of Novosibirsk State University for providing access to the cluster computational resources. This work was supported by the Russian Science Foundation, grant № 21-19-00097. Publisher Copyright: © 2021 Elsevier B.V. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/11

Y1 - 2021/11

N2 - First-principles calculations within the density functional theory of the stability of barium borates of the BaO-B2O3-BaF2 ternary system have been performed at the pressure of up to 10 GPa. A brief summary on the known structures of ambient and high-pressure phases in the BaO–B2O3 and BaF2–Ba3B2O6 subsystems has been provided. In the BaO–B2O3 subsystem the Ba3B2O6, BaB2O4, and BaB4O7 phases tentatively are stable at up to 10 GPa, while the other known ambient-pressure borates Ba5B4O11, Ba2B6O11, and BaB8O13 decompose under the pressure of above 7.1, 0.6, and 2 GPa, respectively. Two new high-pressure polymorphic modifications of BaB2O4 compound, BaB2O4-Pna21 and BaB2O4-Pa3-, stable above 1.0 and 6.1 GPa, respectively, have been predicted. In the BaF2–Ba3B2O6 subsystem Ba7(BO3)4-xF2+3x solid solution is suggested to be stable in the considered pressure range, and Ba5(BO3)3F is suggested to decompose into Ba3B2O6 and Ba7(BO3)4-xF2+3x at pressures above 3–5 GPa. It has been shown that the enthalpy of Ba7(BO3)4-xF2+3x strongly depends on the distribution of the [(BO3)F]4− and [F4]4− groups in the structure. We consider the results obtained as a necessary basis for an experimental study aimed at obtaining barium borates under pressures of up to 10 GPa and studying their structure and properties.

AB - First-principles calculations within the density functional theory of the stability of barium borates of the BaO-B2O3-BaF2 ternary system have been performed at the pressure of up to 10 GPa. A brief summary on the known structures of ambient and high-pressure phases in the BaO–B2O3 and BaF2–Ba3B2O6 subsystems has been provided. In the BaO–B2O3 subsystem the Ba3B2O6, BaB2O4, and BaB4O7 phases tentatively are stable at up to 10 GPa, while the other known ambient-pressure borates Ba5B4O11, Ba2B6O11, and BaB8O13 decompose under the pressure of above 7.1, 0.6, and 2 GPa, respectively. Two new high-pressure polymorphic modifications of BaB2O4 compound, BaB2O4-Pna21 and BaB2O4-Pa3-, stable above 1.0 and 6.1 GPa, respectively, have been predicted. In the BaF2–Ba3B2O6 subsystem Ba7(BO3)4-xF2+3x solid solution is suggested to be stable in the considered pressure range, and Ba5(BO3)3F is suggested to decompose into Ba3B2O6 and Ba7(BO3)4-xF2+3x at pressures above 3–5 GPa. It has been shown that the enthalpy of Ba7(BO3)4-xF2+3x strongly depends on the distribution of the [(BO3)F]4− and [F4]4− groups in the structure. We consider the results obtained as a necessary basis for an experimental study aimed at obtaining barium borates under pressures of up to 10 GPa and studying their structure and properties.

KW - Barium borates

KW - Density functional theory

KW - Phase transitions

UR - http://www.scopus.com/inward/record.url?scp=85111601337&partnerID=8YFLogxK

U2 - 10.1016/j.commatsci.2021.110735

DO - 10.1016/j.commatsci.2021.110735

M3 - Article

AN - SCOPUS:85111601337

VL - 199

JO - Computational Materials Science

JF - Computational Materials Science

SN - 0927-0256

M1 - 110735

ER -