Negative thermal expansion in thiospinel LiGaCr<sub>4</sub>S<sub>8</sub>

ORAL

Abstract

The thiospinel LiGaCr4S8 has been synthesized using solid state synthesis. X-ray diffraction, neutron diffraction, magnetic susceptibility and heat capacity measurements were carried out to study the physical and magnetic properties. The crystal structure of LiGaCr4S8 is derived from the well-known spinel structure, AB2X4, where Li and Ga occupy alternating A sites. The inequivalent cation ordering in A-sites leads to a reduction in the symmetry and the development of a breathing pyrochlore lattice with an alternating array of larger and smaller Cr4 tetrahedra. Negative thermal expansion is observed between 111 and 11 K. No distortion from cubic symmetry was detected, however anomalies in the magnetic properties are observed corresponding to the region of negative thermal expansion. In particular, the magnetic susceptibility deviates from Curie-Weiss behavior coincident with the onset of negative thermal expansion. Whereas the recovery of normal thermal expansion is accompanied by the appearance of a broad peak in the magnetic susceptibility. Taken together, these results suggest strong magnetoelastic coupling in LiGaCr4S8.

*This research is funded by the Gordon and Betty Moore Foundation’s EPIQS Initiative through Grant GBMF4416.

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Presenters

  • Ganesh Pokharel

    • Materials Science and Engineering, University of Tennessee
    • University of Tennessee, Knoxville
    • Univ of Tennessee, Knoxville

Authors

  • Ganesh Pokharel

    • Materials Science and Engineering, University of Tennessee
    • University of Tennessee, Knoxville
    • Univ of Tennessee, Knoxville

  • Andrew Christianson

    • Neutron Scattering Division, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory

  • David Mandrus

    • Department of Materials Science and Engineering, The University of Tennessee
    • Oak Ridge National Lab
    • Oak Ridge National Laboratory
    • Department of Materials Science and Engineering, University of Tennessee
    • University of Tennessee
    • Materials Science and Technology, Oak Ridge National Laboratory
    • Materials Science and Engineering, The University of Tennessee
    • Materials Science and Engineering, University of Tennessee
    • Material Science and Technology Division, Oak Ridge National Laboratory
    • Oakridge National Laboratory
    • University of Tennessee, Knoxville
    • Univ of Tennessee, Knoxville

  • Andrew May

    • Oak Ridge National Lab
    • Materials Science and Technology, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory

  • Hasitha Suria Arachchige

    • Materials Science and Engineering, University of Tennessee
    • Univ of Tennessee, Knoxville

  • Ashfia Huq

    • Oak Ridge National Lab
    • Oak Ridge National Laboratory

  • Georg Ehlers

    • Neutron Scattering Division, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory

  • Simon Kimber

    • Oak Ridge National Laboratory

  • Stuart Calder

    • Oak Ridge National Lab
    • Oak Ridge National Laboratory

  • Lekh Poudel

    • The University of Maryland