ICT2014 Abstracts

Development of new materials with enhanced performance is a crucial step for the next generation of energy solutions. New compounds with high density of states near Fermi level and low thermal conductivity are required for efficient thermoelectrics. We propose to use ternary phosphides of late transition metal (Cu, Zn) with clathrate-like structure as a base for new thermoelectric materials. Electron balance in these compounds is achieved in a way similar to classical Zintl phases assuming closed shell d¹⁰ configuration of transition metal. Adjustment of the valence electron concentration in Ba₈Cu₁₆P₃₀ by partial substitution of Zn for Cu results in a series of structural transformation from orthorhombic to cubic to rhombohedral symmetry. Detailed analysis of these transformations and associated re-distribution of Zn and Cu atoms over framework positions by synchrotron X-ray and neutron powder and single crystal diffraction will be presented. The correlation between crystal structure and thermoelectric properties will be discussed.