Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 19: Frontiers of Electronic Structure Theory: Many-Body Effects on the Nano-Scale I
O 19.6: Vortrag
Dienstag, 17. März 2015, 12:00–12:15, MA 004
Ultra-high temperature properties of ZrC: a fully-anharmonic ab-initio approach — •Andrew Duff1, Dominique Korbmacher2, Albert Glensk2, Blazej Grabowski2, Joerg Neugebauer2, and Mike Finnis1 — 1Department of Physics and Department of Materials, Thomas Young Centre, Imperial College London, Exhibition Road, London SW7 2AZ, UK — 2Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
As a binary end-member of many of the technologically highly interesting MAX phases, as well a useful refractory material in its own right, there is much to be gained from achieving a more accurate first-principles assessment of the behaviour of ZrC at ultra-high temperatures. Exploiting recent developments in finite-temperature density functional theory (DFT) calculations, we provide valuable data at temperatures where the available experimental data is of low accuracy. Within the framework of the UP-TILD approach [Grabowski 2007], the thermal expansion and heat-capacity of ZrC are calculated up to the melting-point. These fully anharmonic results are compared to calculations performed within the widely used quasi-harmonic approximation (QHA), which treats anharmonic effects in only an approximate manner. Sizeable deviations are found close to the melting point, consistent with the strongly anharmonic lattice vibrations present at such temperatures.