Shock induced phase transition of water: Molecular dynamics investigation

Abstract

Molecular dynamics simulations were carried out using numerous force potentials to investigate the shock induced phenomenon of pure bulk liquid water. Partial phase transition was observed at single shock velocity of 4.0 km/s without requirement of any external nucleators. Change in thermodynamic variables along with radial distribution function plots and spectral analysis revealed for the first time in the literature, within the context of molecular dynamic simulations, the thermodynamic pathway leading to formation of ice VII from liquid water on shock loading. The study also revealed information for the first time in the literature about the statistical time-frame after passage of shock in which ice VII formation can be observed and variations in degree of crystallinity of the sample over the entire simulation time of 100 ns.

A metastable phase of shocked bulk single crystal copper: an atomistic simulation study

“…In order to carry out simulations with larger timescales, MSST algorithm (multiscale shock technique 47 which is implemented under the LAMMPS 46 framework and has been tested for simulating a unidirectional planar shock propagation for various class of materials 48 – 51 with sufficient accuracy) has been used to perform simulations up to 10 ns after the passage of shock. The necessary sample details have been given in the Table 2 .…”

High-temperature and high-pressure plastic phase of ice at the boundary of liquid water and ice VII

“…Velocity autocorrelation of oxygen atoms is presented in figure 3 for the shock-equilibrated water samples at 2.5 normalkm normals−1 and 4 normalkm normals−1 shock velocities, along with that of normal water (at 1 bar pressure and 300 K) and ice VII crystal structures (at 300 K and 10 GPa). It has been previously reported [14] that water samples shock equilibrated at 2.5 normalkm normals−1 and 4 normalkm normals−1 represent structures of superheated water and ice VII, respectively. It should be realized that shock compression eventually results in increases in both pressure and temperature.…”

“…The structures of ice VII at different temperature and pressure ranges have also been probed in literature using NMR and XRD/Rietveld studies [30–34]. Molecular dynamic studies demonstrating formation of this eight-coordinated ice VII structure [14] also demonstrate a close match with experimentally observed XRD peaks and/or structure factors. Even though XRD studies can provide a good estimation of the crystal structure, they are unable to probe the hydrogen-bond dynamics of the water molecules.…”

“…Phase transformation of bulk liquid water to an eight-coordinated crystal structure has been demonstrated at an elevated pressure [13] without consideration of shock-wave effects, which typically include the simultaneous increase in temperature and pressure. A molecular dynamics study [14] using different types of force potentials (along with validations of Hugoniot curves obtained from numerous experiments) demonstrated phase transformation of bulk liquid water on shock compression in which the approximate statistical time frame after the passage of shock to nucleate ice VII crystals has been determined along with the percentage of crystallinity of nucleated ice and its temporal evolution. Apart from the above-mentioned studies demonstrating phase transformation of bulk liquid water on shock compression, there have been many other studies highlighting various aspects of the phase-transformation process (which are not particularly necessary for this study), an informative review of which can be obtained from a recent article [15] along with references within it.…”

Enhanced Stimulated Raman Scattering by a Pressure-Controlled Shock Wave in Liquid Water

“…In addition, this limit leads to a certain decrease in shock wave velocity. A. Neogi et al found that within a certain range of shock wave velocities (2.5–3.5 km/s) the temperature generated by the thermal disturbance is reduced in liquid water as shock wave velocities decrease. The shock wave generates an approximately 570 K temperature by thermal disturbance at atmospheric pressure .…”