Berlin 2018 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 22: Microstructure and Phase Transformations
MM 22.1: Talk
Tuesday, March 13, 2018, 10:15–10:30, TC 010
First-principles calculations of the linear elasticity of quartz and implications for pressure induced amorphization — •Christoph Otzen1, Silvana Botti1, and Falko Langenhorst2 — 1Institut für Festkörpertheorie und Optik, Jena, Germany — 2Institut für Geowissenschaften, Jena, Germany
Quartz is a material that is prone to amorphization at high pressures. Numerous studies have been carried out since the discovery of amorphization in the late 1980s to explore mechanisms, structural evolution, and onset of amorphization as a function of static pressure. Quartz displays however a peculiar behavior under shock metamorphism, the process under which a material reacts to dynamic pressure waves with extreme conditions. In this case, quartz develops amorphous lamellae at the nanometer scale with sharp crystalline-amorphous boundaries and most strikingly, in particular crystallographic orientations.
Here, we investigate the directional dependence of some mechanical properties of quartz in the approximation of linear elasticity and compare our results with the orientations of amorphous lamellae to gain insight into their formation mechanism. We tackle the problem by calculating second-order elastic coefficients by means of density functional theory. Our first calculations of stress-strain relations for all directions indicate indeed structural changes over pressure that are consistent with anisotropic amorphization of quartz.