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Séminaires Chimie ED459

Calculating the thermoelectric properties of zinc-antimonides | High throughput screening of stability and thermoelectric properties in the transition metal silicides

Prof. Georg Madsen (ICAMS Interdisciplinary Centre for Advanced Materials Simulation, Ruhr-Universität Bochum, Allemagne – Professeur Invité Chaire Total Fondation Balard)

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Les Jeudis 26 septembre et 04 octobre 2013 à 13h45
UM2, salle de cours SC-16.01

Le Prof. Georg Madsen présentera deux séminaires dans le cadre de l’ED459 :

1. Jeudi 26 septembre :
Calculating the thermoelectric properties of zinc-antimonides

The electronic structure and transport properties of the 1:1 phase of Zn-Sb will be discussed based on the boltzmann transport equation. It will be shown how the conduction band of ZnSb has several minima stemming from increased bonding between distant neighbors at special k-points. from literature, the carrier concentrations, band gaps, and relaxation times of the compounds are determined. The thermodynamic stability of intrinsic defects in ZnSb are studied. It is shown that the low formation energy of negatively charged Zn defects limit pins the chemical potential to the valence bands, thereby explaining the experimentally observed p-type behavior. Finally, we introduce a simple Klemens-Callaway like model of the thermal conductivity and use it to explain the low thermal conductivity of the 1:1 and especially the 4:3 phase.

2. Jeudi 03 octobre :
High throughput screening of stability and thermoelectric properties in the transition metal silicides

The phase stability, electronic structure and transport properties of
binary 3d, 4d and 5d transition metal silicides are investigated using highthroughput density functional calculations. An overall good agreement is found
between the calculated 0K phase diagrams and experiment. We introduce
descriptors for the phase-stability and thermoelectric properties and hereby
identify several candidates with potential for thermoelectric applications. This
includes known thermoelectrics like Mn4Si7, β-FeSi2, Ru2Si3 and CrSi2 as well as new potentially meta-stable materials like Rh3Si5, Fe2Si3 and an orthorhombic CrSi2 phase. Analysis of the electronic structure shows that the gap formation in most of the semiconducting transition metal silicides can be understood with simple hybridization models. The observed trends in the structural stability are analysed in terms of a simple tight-binding model.

Contact local ICGM : Prof. Philippe Jund (équipe MESO)

Agenda

séminaire

  • Jeudi 26 septembre 2013 13:45-15:00 -

    Calculating the thermoelectric properties of zinc-antimonides

    Résumé : Séminaire Chimie ED459 – Georg Madsen

    Lieu : UM2, salle SC-16.01


  • Jeudi 3 octobre 2013 13:45-15:00 -

    High throughput screening of stability and thermoelectric properties in the transition metal silicides

    Résumé : Séminaire Chimie ED459 – Georg Madsen

    Lieu : UM2, salle SC-16.01


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