Revisiting Thermodynamics in (Lif, Naf, Kf, Crf2)-Crf3 by First-Principles Calculations and Calphad Modeling

49 Pages Posted: 19 Mar 2024

See all articles by Rushi Gong

Rushi Gong

Pennsylvania State University

Shun-Li Shang

Pennsylvania State University - Department of Materials Science and Engineering

Yi Wang

Pennsylvania State University - Department of Materials Science and Engineering

Jorge Paz Soldan Palma

Pennsylvania State University - Department of Materials Science and Engineering

Hojong Kim

Pennsylvania State University - Department of Materials Science and Engineering

Zi-Kui Liu

Pennsylvania State University - Department of Materials Science and Engineering

Abstract

The thermodynamic description of the (LiF, NaF, KF, CrF2)-CrF3 systems has been revisited, aiming for a better understanding of the effects of Cr on the FLiNaK molten salt. First-principles calculations based on density functional theory (DFT) were performed to determine the electronic and structural properties of each compound, including the formation enthalpy, volume, and bulk modulus. DFT-based phonon calculations were carried out to determine the thermodynamic properties of compounds, for example, enthalpy, entropy, and heat capacity as functions of temperature. Phonon-based thermodynamic properties show a good agreement with experimental data of binary compounds LiF, NaF, KF, CrF3, and CrF2, establishing a solid foundation to determine thermodynamic properties of ternary compounds as well as to verify results estimated by the Neumann-Kopp rule. Additionally, DFT-based ab initio molecular dynamics (AIMD) simulations were employed to predict the mixing enthalpies of liquid salts. Using DFT-based results and experimental data in the literature, the (LiF, NaF, KF, CrF2)-CrF3 system has been remodeled in terms of the CALculation of PHAse Diagrams (CALPHAD) approach using the modified quasichemical model with quadruplet approximation (MQMQA) for liquid. Calculated phase stability in the present work shows an excellent agreement with experiments, indicating the effectiveness of combining DFT-based total energy, phonon, and AIMD calculations, and CALPHAD modeling to provide the thermodynamic description in complex molten salt systems.

Keywords: FLiNaK, Molten Salts, First-principles calculations, Phonon, AIMD, CALPHAD modeling

Suggested Citation

Gong, Rushi and Shang, Shun-Li and Wang, Yi and Paz Soldan Palma, Jorge and Kim, Hojong and Liu, Zi-Kui, Revisiting Thermodynamics in (Lif, Naf, Kf, Crf2)-Crf3 by First-Principles Calculations and Calphad Modeling. Available at SSRN: https://ssrn.com/abstract=4764712 or http://dx.doi.org/10.2139/ssrn.4764712

Rushi Gong (Contact Author)

Pennsylvania State University ( email )

Shun-Li Shang

Pennsylvania State University - Department of Materials Science and Engineering ( email )

Yi Wang

Pennsylvania State University - Department of Materials Science and Engineering ( email )

Jorge Paz Soldan Palma

Pennsylvania State University - Department of Materials Science and Engineering ( email )

Hojong Kim

Pennsylvania State University - Department of Materials Science and Engineering ( email )

University Park
State College, PA 16802
United States

Zi-Kui Liu

Pennsylvania State University - Department of Materials Science and Engineering

University Park
State College, PA 16802
United States

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