Enhanced absorption of hydrogen in ball milled lanthanum for hydride formation
ORAL
Abstract
Superhydride compounds tend to exhibit high temperature superconductivity. A challenge with forming these compounds is that it is hard to incorporate the large over-stoichiometric amounts of hydrogen needed to promote superconductivity into a reacted product. High pressures and temperatures are required to form the presently known superhydride compounds with high transition temperatures. We attempt to improve the reactivity to hydrogen in elemental lanthanum using a cryogenic ball milling technique. A lanthanum precursor was milled for different lengths of time and exposed to solid ammonia borane. The resulting mix was exposed to high pressure in a diamond anvil cell at room temperature and X-ray diffraction was performed at HPCAT to explore any phase transformations and to measure the unit cell volume in order to infer the hydrogen content. With increased milling time, we were able to improve the hydrogen loading so as to form LaHx of various stoichiometries.
*This work was funded by the Laboratory Directed Research and Development Program at Sandia National Laboratories (SNL). SNL is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. DOE's National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. DOE or the United States Government. Portions of this work were performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The instrumentation and facilities used were supported by DOE/BES (DE-FG02-99ER45775, VVS), the U.S. DOE/National Nuclear Security Administration (DE-NA-0002006, CDAC; and DE-NA0001974, HPCAT), and the National Scie
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Presenters
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Peter A Sharma
- Sandia National Laboratories