Thermal equation of state and thermodynamic properties of molybdenum at high pressures

Konstantin D. Litasov, Peter I. Dorogokupets, Eiji Ohtani, Yingwei Fei, Anton Shatskiy, Igor S. Sharygin, Pavel N. Gavryushkin, Sergey V. Rashchenko, Yury V. Seryotkin, Yiji Higo, Kenichi Funakoshi, Artem D. Chanyshev, Sergey S. Lobanov

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Abstract

A comprehensive P-V-T dataset for bcc-Mo was obtained at pressures up to 31 GPa and temperatures from 300 to 1673 K using MgO and Au pressure calibrants. The thermodynamic analysis of these data was performed using high-temperature Birch-Murnaghan (HTBM) equations of state (EOS), Mie-Grüneisen-Debye (MGD) relation combined with the room-temperature Vinet EOS, and newly proposed Kunc-Einstein (KE) approach. The analysis of room-temperature compression data with the Vinet EOS yields V0 = 31.14 ± 0.02 Å3, KT = 260 ± 1 GPa, and K T′ = 4.21 ± 0.05. The derived thermoelastic parameters for the HTBM include (∂KT/∂T)P = -0.019 ± 0.001 GPa/K and thermal expansion α = a0 + a1T with a0 = 1.55 (± 0.05) × 10-5 K-1 and a1 = 0.68 (± 0.07) × 10-8 K-2. Fitting to the MGD relation yields γ0 = 2.03 ± 0.02 and q = 0.24 ± 0.02 with the Debye temperature (θ0) fixed at 455-470 K. Two models are proposed for the KE EOS. The model 1 (Mo-1) is the best fit to our P-V-T data, whereas the second model (Mo-2) is derived by including the shock compression and other experimental measurements. Nevertheless, both models provide similar thermoelastic parameters. Parameters used on Mo-1 include two Einstein temperatures ΘE10 = 366 K and ΘE20 = 208 K; Grüneisen parameter at ambient condition γ0 = 1.64 and infinite compression γ = 0.358 with β = 0.323; and additional fitting parameters m = 0.195, e 0 = 0.9 × 10-6 K-1, and g = 5.6. Fixed parameters include k = 2 in Kunc EOS, mE1 = mE2 = 1.5 in expression for Einstein temperature, and a0 = 0 (an intrinsic anharmonicity parameter). These parameters are the best representation of the experimental data for Mo and can be used for variety of thermodynamic calculations for Mo and Mo-containing systems including phase diagrams, chemical reactions, and electronic structure.

Original languageEnglish
Article number093507
JournalJournal of Applied Physics
Volume113
Issue number9
DOIs
Publication statusPublished - 2013 Mar 7

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Litasov, K. D., Dorogokupets, P. I., Ohtani, E., Fei, Y., Shatskiy, A., Sharygin, I. S., Gavryushkin, P. N., Rashchenko, S. V., Seryotkin, Y. V., Higo, Y., Funakoshi, K., Chanyshev, A. D., & Lobanov, S. S. (2013). Thermal equation of state and thermodynamic properties of molybdenum at high pressures. Journal of Applied Physics, 113(9), [093507]. https://doi.org/10.1063/1.4794127