Hydrogen‐Release Reaction of a Complex Transition Metal Hydride with Covalently Bound Hydrogen and Hydride Ions
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- Toyoto Sato
- Institute for Materials Research Tohoku University Sendai Miyagi 980-8577 Japan
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- Luke L. Daemen
- Neutron Scattering Division Spallation Neutron Source Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
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- Yongqiang Cheng
- Neutron Scattering Division Spallation Neutron Source Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
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- Anibal J. Ramirez‐Cuesta
- Neutron Scattering Division Spallation Neutron Source Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA
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- Kazutaka Ikeda
- Institute of Materials Structure Science High Energy Accelerator Research Organization Tsukuba Ibaraki 305-0801 Japan
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- Takuma Aoki
- Institute for Materials Research Tohoku University Sendai Miyagi 980-8577 Japan
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- Toshiya Otomo
- Institute of Materials Structure Science High Energy Accelerator Research Organization Tsukuba Ibaraki 305-0801 Japan
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- Shin‐ichi Orimo
- Institute for Materials Research Tohoku University Sendai Miyagi 980-8577 Japan
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説明
<jats:title>Abstract</jats:title><jats:p>The hydrogen‐release reaction of a complex transition metal hydride, LaMg<jats:sub>2</jats:sub>NiH<jats:sub>7</jats:sub>, composed of La<jats:sup>3+</jats:sup>, 2×Mg<jats:sup>2+</jats:sup>, [NiH<jats:sub>4</jats:sub>]<jats:sup>4−</jats:sup> and 3×H<jats:sup>−</jats:sup>, was studied by thermal analyses, powder X‐ray, and neutron diffraction and inelastic neutron scattering. Upon heating, LaMg<jats:sub>2</jats:sub>NiH<jats:sub>7</jats:sub> released hydrogen at approximately 567 K and decomposed into LaH<jats:sub>2−3</jats:sub> and Mg<jats:sub>2</jats:sub>Ni. Before the reaction, covalently bound hydrogen (H<jats:sup>c</jats:sup>°<jats:sup>v.</jats:sup>) in [NiH<jats:sub>4</jats:sub>]<jats:sup>4−</jats:sup> exhibited a larger atomic displacement than H<jats:sup>−</jats:sup>, although a weakening of the chemical bonds around [NiH<jats:sub>4</jats:sub>]<jats:sup>4−</jats:sup> and H<jats:sup>−</jats:sup> was observed. These results indicate the precursor phenomenon of a hydrogen‐release reaction, wherein there is a large atomic displacement of H<jats:sup>c</jats:sup>°<jats:sup>v.</jats:sup> that induces the hydrogen‐release reaction rather than H<jats:sup>−</jats:sup>. As an isothermal reaction, LaMg<jats:sub>2</jats:sub>NiH<jats:sub>7</jats:sub> formed LaMg<jats:sub>2</jats:sub>NiH<jats:sub>2.4</jats:sub> at 503 K in vacuum for 48 h, and LaMg<jats:sub>2</jats:sub>NiH<jats:sub>2.4</jats:sub> reacted with hydrogen to reform LaMg<jats:sub>2</jats:sub>NiH<jats:sub>7</jats:sub> at 473 K under 1 MPa of H<jats:sub>2</jats:sub> gas pressure for 10 h. These results revealed that LaMg<jats:sub>2</jats:sub>NiH<jats:sub>7</jats:sub> exhibited partially reversible hydrogen‐release and uptake reactions.</jats:p>
収録刊行物
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- ChemPhysChem
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ChemPhysChem 20 (10), 1392-1397, 2019-01-23
Wiley