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MM: Fachverband Metall- und Materialphysik

MM 22: Microstructure and Phase Transformations

MM 22.1: Vortrag

Dienstag, 13. März 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.