Atomistic modeling of high-pressure silica crystallization under dynamic compression
Abstract/Contents
- Abstract
- Understanding the kinetics of shock-compressed SiO2 is of great importance for mitigating optical damage for high-intensity lasers and for understanding meteoroid impacts. Experimental work has placed some thermodynamic bounds on the formation of high-pressure phases of this material, but the formation kinetics and underlying microscopic mechanisms are yet to be elucidated. In this study, by employing multi-scale molecular dynamics studies of shock-compressed fused silica and quartz, we find that silica transforms into a poor glass former that subsequently exhibits ultrafast crystallization within a few nanoseconds. We also find that, as a result of the formation of such an intermediate disordered phase, the transition between silica polymorphs obeys a homogeneous reconstructive nucleation and grain growth model. We construct a quantitative model of nucleation and grain growth, and compare its predictions with high-pressure silica crystal grain sizes observed in laser-induced damage and meteoroid impact events. Moreover, we have studied the quantum nuclear effects for high-pressure silica crystallization. While quantum nuclear effects play important roles in shock-induced chemical reactions and phase transitions, they are absent in classical atomistic shock simulations. To address this shortcoming, we couple the shock simulation with a colored-noise Langevin thermostat. We find that this semiclassical approach gives shock temperatures as much as 7% higher than classical simulations near the onset of crystallization in silica. We have also studied the impact of this approach on the kinetics of crystallization and the position of high-pressure silica melt line.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2017 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Shen, Yuan |
|---|---|
| Associated with | Stanford University, Department of Physics. |
| Primary advisor | Doniach, S |
| Primary advisor | Reed, Evan J |
| Thesis advisor | Doniach, S |
| Thesis advisor | Reed, Evan J |
| Thesis advisor | Cai, Wei |
| Advisor | Cai, Wei |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Yuan Shen. |
|---|---|
| Note | Submitted to the Department of Physics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2017. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2017 by Yuan Shen
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