Unusual structural evolution in KCuF$_3$ at high temperatures by neutron powder diffraction

ORAL

Abstract

High-resolution neutron powder diffraction has been performed to study the structural evolution of the perovskite KCuF$_3$ at temperatures up to 900 K. Results of the Rietveld refinement reveal an unusual site distortion that increases as temperature increases. In contrast to the widely accepted assumption that a cooperative Jahn-Teller transition may occur at 800 K, no phase transition was observed up to 900 K. We have made a comparative study of the Jahn-Teller distortion in fluorides and oxides with variables such as temperature, pressure, and the dilution by non-Jahn-Teller active ions in these compounds.

*This work was supported by NSF (DMR 0904282, DMR 1122603) and the Robert A. Welch foundation (Grant F-1066).

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Authors

  • Luke G. Marshall

    • Materials Science and Engineering Program, University of Texas at Austin

  • Jianshi Zhou

    • Materials Science and Engineering Program, University of Texas at Austin

  • Jianzhong Zhang

    • LANSCE Division, Los Alamos National Laboratory

  • Jiantao Han

    • LANSCE Division, Los Alamos National Laboratory

  • Sven C. Vogel

    • LANSCE Division, Los Alamos National Laboratory

  • Xiaohui Yu

    • LANSCE Division, Los Alamos National Laboratory

  • Yusheng Zhao

    • LANSCE Division, Los Alamos National Laboratory; Department of Physics and Astronomy, University of Nevada

  • Maria-Teresa Fernandez-Diaz

    • Institut Laue-Langevin

  • Jinguang Cheng

    • Materials Science and Engineering Program, University of Texas at Austin; Institute for Solid State Physics, University of Tokyo, Kashiwanoha

  • John B. Goodenough

    • Materials Science and Engineering Program, University of Texas at Austin