Quasi-Low-Dimensional Reduced Transition Metal Oxides: Synthesis and Characterization

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9314605 Greenblatt Experience shows that materials with novel behavior are likely to be discovered when competing electronic interactions exist. In low-dimensional materials, the interplay of competing electronic interactions is enhanced. The object of this project is the synthesis and characterization of new reduced transition metal compounds with quasi-low-dimensional properties. Systems of interest include: (1) transition metal (Nb, Ta and W) bronzes and (2) molybdenum, niobium, and rhenium cluster compounds. The focus of the experimental program is to synthesize new materials of strongly-correlated electron systems that are on the verge of electronic and structural instabilities, and to fine tune the competing electronic interactions through the unstable region in a controlled way. Particular emphasis will be placed on the preparation of single crystal specimens to study the structural and orientation dependent physical properties. Single crystal measurements of the electrical resistivity, magnetic susceptibility, specific heat as a function of temperature, DTA, ESR, FTIR, optical and XANE spectroscopies will be used to characterize samples of interest. Structural and physical property relationships will be stressed. Transitions associated with the onset of charge density waves (CDW) and/or superconductivity will be sought and characterized. These studies are expected to yield novel materials, provide fundamental insights into correlated electronic behavior and uHimately allow the enhancement and control of electronic instabilities that lead to interesting and useful macroscopic properties. ***