Dresden 2020 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 18: Poster Session I

MM 18.17: Poster

Monday, March 16, 2020, 18:15–20:00, P4

Ab initio opto electronic properties of magnesium silicide alloys — •Juan Guerra, Marcel Giar, Carsten Mahr, Michael Czerner, and Christian Heiliger — Justus Liebig University Giessen, Institut für Theoretische Physik, Giessen, Germany

Due to an increasing interest in the use of environmentally friendly materials for energy conversion, we present a comprehensive ab initio analysis of the opto electronic properties of magnesium silicide materials. These materials have shown an enhancement in the thermoelectric performance when alloyed by Sn as consequence of the convergence of the conduction bands and the reduction of thermal transport. Mg2Si and Mg2Ge have also be shown to be thermodynamically unstable when alloyed by Sn for compositions between the so-called miscibility gap. Our calculations are based on the full-relativistic Green's function Korringa, Kohn and Rostocker (KKR) formalism, within the coherent potential approximation (CPA). We perform total energy calculations to obtain optimal structural properties and relative formation energies to interpret the material's instability. Using the Bloch spectral density function (BSF), we interpolate and map the electronic bands to extract relevant parameters for transport, e.g., band gaps and effective masses within the single parabolic band approximation. We also provide calculations of the contributions to the dielectric function due to direct interband transitions via the joint density of states (JDOS).