Yuri Grin

Abstract:

One of the key issues in the further understanding of chemical ad physical behaviors of intermetallic compounds is complexity of their crystal structures. Structural complexity of intermetallic compounds may be described from the points of view of crystallographic features (number of atoms, symmetry), of chemical and crystallographic order/disorder, or of thermodynamic factors (phase diagrams, formation reactions), etc.. On base of crystallographic description, a special family of intermetallic compounds – the so-called complex metallic alloys or phases (CMA) – was defined. Neither electronic nor thermal transport behaviors follow strictly the crystallographic understanding of structural complexity in CMA. Nevertheless, recently was shown that the reduced lattice thermal conductivity of intermetallic type-I clathrates without vacancies and with respect to such with ordered vacancies suggests that disordered vacancies disturb the heat transport more efficiently as the electronic transport. Further insights are achieved considering the spatial separation of regions with different chemical bonding in the content of structural complexity.