Density Functional Theory (DFT) simulations of porous tantalum pentoxide

18th APS-SCCM; 24th AIRAPT

Cochrane, K.R.^1 ; Vogler, T.J.^1 ; Desjarlais, M.P.^1 ; Mattsson, T.R.^1

Sandia National Laboratories, PO Box 5800, Albuquerque

MS

87185, United States^1

关键词: Complex polymers;    Equation of state;    High-fidelity;    Initial density;    Mie-Gruneisen;    Model approximates;    Porous tantalums;    Tantalum pentoxide;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/500/3/032005/pdf
DOI  :  10.1088/1742-6596/500/3/032005

来源: IOP

【 摘 要 】

Density Functional Theory (DFT) based molecular dynamics has been established as a method capable of yielding high fidelity results for many materials at a wide range of pressures and temperatures and has recently been applied to complex polymers such as polyethylene, compounds such as ethane or CO2, and oxides such as MgO. We use this method to obtain a Grïneisen Γ and thereby build a Mie-Grüneisen equation of state (EOS) and a Rice-Walsh EOS for tantalum pentoxide (Ta2O5or tantala) and compare to experimental data. The experimental data have initial densities (ρ00) of approximately 1.13, 3, and 7.4 g/cm3reduced from a crystalline of 8.36 g/cm3. We found that r becomes constant at higher temperatures and pressure, but is a function of both density and temperature at lower densities and temperatures. Finally, the Mie-Gruneisen EOS is adequate for modeling the slightly distended Hugoniot with an initial density of 7.4 g/cm3however it is inadequate for the more porous Hugoniot, while the Rice-Walsh EOS combined with a P-λ crush model approximates the experimental data quite well.