TY - JOUR
T1 - Crystal structure and charge density analysis of Li2NH by synchrotron X-ray diffraction
AU - Noritake, T.
AU - Nozaki, H.
AU - Aoki, M.
AU - Towata, S.
AU - Kitahara, G.
AU - Nakamori, Y.
AU - Orimo, S.
N1 - Funding Information:
The synchrotron radiation experiments were performed at the SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2003B0195-NI-np). This work was partially supported by the New Energy and Industrial Technology Development Organization (NEDO), “Development of Safe Utilization Technology and an Infrastructure for Hydrogen Use (2003–2004)”. The authors express their heartfelt thanks to S. Yamaguchi, N. Ohba and K. Miwa for their valuable support and discussion.
PY - 2005/5/3
Y1 - 2005/5/3
N2 - Complex hydrides, such as lithium amide (LiNH2) and lithium imide (Li2NH), have recently been noticed as one of the most promising materials for reversible hydrogen storage. In this paper, we reveal the bonding nature of hydrogen in Li2NH crystal by synchrotron powder X-ray diffraction measurement at room temperature. The crystal structure was refined by Rietveld method and the charge density distribution was analyzed by maximum entropy method (MEM). The Li2NH crystal is anti-fluorite type structure (space group Fm3̄m) consisting of Li and NH. Hydrogen atom occupies randomly the 48h (Wyckoff notation) sites around N atom. The refined lattice constant is a = 5.0742(2) Å. The charge density distribution around NH anion in Li2NH is almost spherical. The number of electrons within the sphere around the Li and NH is estimated from the obtained charge density distribution. As the result, the ionic charge is expressed as [Li 0.99+]2[NH]1.21-. Therefore, it is confirmed experimentally that Li2NH is ionically bonded.
AB - Complex hydrides, such as lithium amide (LiNH2) and lithium imide (Li2NH), have recently been noticed as one of the most promising materials for reversible hydrogen storage. In this paper, we reveal the bonding nature of hydrogen in Li2NH crystal by synchrotron powder X-ray diffraction measurement at room temperature. The crystal structure was refined by Rietveld method and the charge density distribution was analyzed by maximum entropy method (MEM). The Li2NH crystal is anti-fluorite type structure (space group Fm3̄m) consisting of Li and NH. Hydrogen atom occupies randomly the 48h (Wyckoff notation) sites around N atom. The refined lattice constant is a = 5.0742(2) Å. The charge density distribution around NH anion in Li2NH is almost spherical. The number of electrons within the sphere around the Li and NH is estimated from the obtained charge density distribution. As the result, the ionic charge is expressed as [Li 0.99+]2[NH]1.21-. Therefore, it is confirmed experimentally that Li2NH is ionically bonded.
KW - Charge density
KW - Complex hydride
KW - Hydrogen storage materials
KW - Synchrotron radiation
KW - X-ray diffraction
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U2 - 10.1016/j.jallcom.2004.09.063
DO - 10.1016/j.jallcom.2004.09.063
M3 - Article
AN - SCOPUS:16244387896
SN - 0925-8388
VL - 393
SP - 264
EP - 268
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
IS - 1-2
ER -