The Synthesis & Physical Properties of Solid State CompoundsContaining Condensed Metal Clusters Via Controlled Nucleation of Amorphous Intermediates

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This proposal emphasizes the synthesis of new ternary tungsten and niobium chalcogenide compounds that contain discrete clusters of transition metal atoms. This important class of materials exhibits a host of interesting properties ranging from catalytic activity to magnetism and superconductivity. The synthetic approach to be used is based upon the utilization of superlattice reactants, which involves separating the two key steps of a solid-state reaction - interdiffusion of the reactant, and crystallization of the products. Interdiffusion to an amorphous state is accomplished by tailoring the structure of the initial superlattice reactant. The crystallization of the resulting amorphous intermediate is controlled via stoichiometry and/or through seeding of the composite with isostructural analogues. Materials characterization and the further development of this synthetic approach is a significant part of the proposed research, as is extending the range of properties exhibited by these potentially functional materials.