College Park, Maryland June 6 - 10 , 2004
WP70: PDF analysis of local distortions in Ti2Sb and CeTe3
H. J. Kim, X. Qiu, S. J. L. Billinge (Department of Physics & Astronomy, and Center for Fundamental Materials Research Michigan State University, East Lansing, Michigan 48824), S. Derakhshan, A. Assoud, E. Dashjav, H. Kleinke (Department of Chemistry University of Waterloo, Waterloo, ON, Canada N2L 3G), C. Malliakas, T. Kyratsi, M. G. Kanatzidis (Department of Chemistry, and Center for Fundamental Materials Research Michigan State University, East Lansing, Michigan 48824), P.J. Chupas, C.P. Gray (State University of New York, Stony Brook, NY 11794-2275), P.L. Lee (Advanced Photon Source, Argonne National Laboratory, Argonne, IL)
Recent years have seen enormous progress in developing novel electronic materials. Mounting evidence suggests that structures, defects, and interactions on nanometer length-scales are intimately connected to their remarkable properties. Therefore, precisely resolving these structures is inevitable for the ultimate understanding of the properties of the materials and it requires advanced local techniques such as atomic Pair Distribution Function (PDF) analysis. Local distortions in two materials, Ti2Sb and CeTe3, are investigated using PDF analysis. The single crystal X-ray study on a new binary antimonide Ti2Sb suggests a new type of distortion in the Ti square planar nets. The PDF analysis on this system verifies that Ti nets deform to squares and rhombs in order to enhance Ti-Ti bonding. Formation of 1¡¿1¡¿7 superstructure on a layered chalcogenide CeTe3, also known as a charge-density wave material, is observed by the single crystal X-ray and TEM studies. The chemical, physical, and electronic properties of this material are largely decided by Te square nets whose average Te-Te bond (~3.1 Å) is larger than the normal covalent Te-Te bond (~2.8 Å). The PDF measurements suggest that local structural distortions occur in the Te square nets forming short bonds around 2.8 Å resulting in a 1:1:7 superstructure.
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