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Innovative & Complex Metal-Rich Materials

This project strives (i) to uncover and ultimately design new families of intermetallic phases; (ii) to understand the factors that stabilize both new and known metal-rich phases by combining exploratory synthesis and temperature-dependent structure determinations with electronic structure theory; and (iii) to establish structure-property relationships for complex metal-rich materials as related to both practical as well as fundamental issues, e.g., thermoelectric, magnetocaloric, catalytic, and magnetic behavior. Targeted compound classes include, but are not limited to, Hume-Rothery types, polar intermetallics, quasicrystalline and approximant phases, and complex metallic alloys of transition metals.  Significant focus includes (i) compounds involving reduced environments for elements of the late 5th and 6th period transition elements (Pd, Pt, Ag, Au), which offer filled d-bands and relativistic enhancements of chemical bonding; (ii) Li-rich intermetallics, taking advantage of Li’s dual role of both an active as well as an electronegative metal in chemically reduced environments; and (iii) 3d metal systems grown in reactive and eutectic fluxes. 

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

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  • Cover art showing V. Smetana and A.-V. Mudring's work in Angewandte Chemie

    A double salt of cesium platinum and cesium hydride has been made for the first time. Simple salts, like sodium chloride, contain one positively charged element and one negatively charged element. This double salt contains two anions (Pt2- and H-) and one cation (Cs+). Einstein’s Theory of Relativity helps explain how this is possible.

  • The unusual combination of the bonding ability of gold and the magnetic nature of manganese is shown in a series of new ternary compounds.  Explorations in new intermetallic chemistry led to the discovery of the new series of materials, comprised of gold, manganese, and a rare-earth metal element (either gadolinium or yttrium).  The new materials exploit the properties of gold, known for its high electronegativity (ability to attract electrons), and manganese, an element known for its magnetic properties.

  • A new material made from three elements — yttrium, manganese and gold — woven together in an unusual crystalline lattice shows surprisingly diverse characteristics for each element. The manganese electrons are localized at the manganese sites, whereas the yttrium and gold electrons are delocalized. Yttrium in this rhombohedral lattice tends to give up electrons and thus be positively charged whereas the gold prefers to take on electrons. The magnetic characteristics are also unusual with electron spins strongly aligned only at the manganese sites.

  • Gold atoms can be the key to making new materials with fascinating and frequently beautiful arrangements of atoms. For example, materials made from gold, sodium and gallium contain gold atoms arranged into tetrahedra, rods of hexagonal stars, or diamond-like three-dimensional frameworks.  For certain gold concentrations, gold interacts in a novel way with sodium and stabilizes the formation of icosahedra.

  • Discovery and detailed investigations of the ternary calcium–gold–bismuth system revealed, for the first time, the chemistry of a rare, spinodal decomposition and helped translate the classical Gibbs criteria for phase stability and spinodal decomposition into modern, chemist-friendly language.

  • An international team of researchers has discovered a new type of defect in an unconventional material known as a quasicrystal. Mysterious nanodomains observed on the surfaces of quasicrystals led to the discovery. Quasicrystals were already known to have a unique defect type, known as a phason flip, which can form at the surface. The new defect type is related, but unlike the phason flip is not restricted to the surface; it bridges the surface and the bulk.