Synthesis and Characterization of Calcium Hydrides at High Pressure-Temperature Conditions

ORAL

Abstract


With the report of high temperature superconductivity in H3S1 and the success of the theoretical predictions accompanying that discovery2, there have been many theoretical predictions of superconductivity in related systems3 as well as other systems. One of the attractive predictions relates to the possibility of clathrate like structures in the calcium system4. We report details of our in-situ synchrotron xray diffraction studies on Ca-H mixtures in the pressure range 5-200 GPa and 300-2000 K. At low pressures, not surprisingly, we found that CaH2 is formed but does not dissociate or transform to any higher hydride. We report results on a very detailed set of in-situ synchrotron XRD experiments carried out at 16-ID-B. Using a combination of theory and experiment, we have identified five different hydrides. Details of these synthesis studies as well as possibility of superconducting phases in these class of hydrides will be presented.

1 Drozdov, A. P., et. al. S. I. Nature 525, 73-76 (2015).
2 Li, Y., et. al . J. Chem. Phys. 140, 174712-174719 (2014).
3 Duan, D. et al. . Scientific Reports 4, 6968, (2014).
4 Wang, H., et. al. Proc. Nat. Acad. Sci. 109, 6463-6466 (2012).

–

Presenters

  • Maddury Somayazulu

    Geophysical Laboratory, Carnegie Institution of Washington, Geophysical Laboratory, Carnegie Inst of Washington, Carnegie Inst of Washington

Authors

  • Maddury Somayazulu

    Geophysical Laboratory, Carnegie Institution of Washington, Geophysical Laboratory, Carnegie Inst of Washington, Carnegie Inst of Washington

  • Ajay Mishra

    Geophysical Laboratory, Carnegie Institution of Washington, Geophysical Laboratory, Carnegie Inst of Washington, Carnegie Inst of Washington

  • Muhtar Ahart

    Geophysical Laboratory, Carnegie Inst of Washington, Carnegie Institute of Washington

  • Hanyu Liu

    Geophysical Laboratory, Carnegie Institution for Science, Geophysical Laboratory, Carnegie Institution of Washington, Geophysical Laboratory, Carnegie Inst of Washington

  • Zachary Geballe

    Geophysical Laboratory, Carnegie Institution of Washington, Geophysical Laboratory, Carnegie Inst of Washington

  • Maria Baldini

    Geophysical Laboratory, Carnegie Institution of Washington, Geophysical Laboratory, Carnegie Inst of Washington, Carnegie Institution of Washington

  • Yue Meng

    HPCAT, Carnegie Institution of Washington, Geophysical Laboratory, Carnegie Inst of Washington, Carnegie Institution of Washington, High Pressure Collaborative Access Team (HPCAT), Geophysical Laboratory

  • Russell Hemley

    Institute of Materials Science and Civil and Environmental Engineering, George Washington University, School of Engineering and Applied Science, George Washington University, George Washington University, Department of Civil and Environmental Engineering, The George Washington University