TY - JOUR
T1 - Dehydriding reaction of Mg(NH2)2-LiH system under hydrogen pressure
AU - Aoki, M.
AU - Noritake, T.
AU - Kitahara, G.
AU - Nakamori, Y.
AU - Towata, S.
AU - Orimo, S.
N1 - Funding Information:
The authors would like to thank K. Miwa and N. Ohba for valuable discussion. 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 (2003–2005)”.
PY - 2007/1/31
Y1 - 2007/1/31
N2 - The dehydriding and structural properties of the 3Mg(NH2)2 + 12LiH system under hydrogen pressure were investigated using the pressure-composition (p-c) isotherm measurement and X-ray diffraction (XRD) analysis. Two distinct regions, a plateau region and a sloping region, can be seen on the p-c isotherms and the amount of the desorbed hydrogen at 523 K was 4.9 mass%. The enthalpy of hydrogenation calculated using a van't Hoff plot was -46 kJ/mol H2. The dehydriding reaction was proposed for the 3Mg(NH2)2 + 12LiH system based on the obtained p-c isotherms and XRD profiles and chemical valences of Li, Mg, N, and H. In the plateau region on the p-c isotherm, Mg(NH2)2, Li4Mg3(NH2)2(NH)4 (tetragonal), and LiH phases coexist and the molar ratio of the Li4Mg3(NH2)2(NH)4 phase increases (while those of Mg(NH2)2 and LiH phases decrease) with the amount of the desorbed hydrogen. On the other hand, the mixture of Li4+xMg3(NH2)2-x(NH)4+x + (8-x)LiH (0 ≤ x ≤ 2) is formed and the lattice volume of the Li4+xMg3(NH2)2-x(NH)4+x phase continuously increases with the amount of the desorbed hydrogen in the sloping region on the p-c isotherm.
AB - The dehydriding and structural properties of the 3Mg(NH2)2 + 12LiH system under hydrogen pressure were investigated using the pressure-composition (p-c) isotherm measurement and X-ray diffraction (XRD) analysis. Two distinct regions, a plateau region and a sloping region, can be seen on the p-c isotherms and the amount of the desorbed hydrogen at 523 K was 4.9 mass%. The enthalpy of hydrogenation calculated using a van't Hoff plot was -46 kJ/mol H2. The dehydriding reaction was proposed for the 3Mg(NH2)2 + 12LiH system based on the obtained p-c isotherms and XRD profiles and chemical valences of Li, Mg, N, and H. In the plateau region on the p-c isotherm, Mg(NH2)2, Li4Mg3(NH2)2(NH)4 (tetragonal), and LiH phases coexist and the molar ratio of the Li4Mg3(NH2)2(NH)4 phase increases (while those of Mg(NH2)2 and LiH phases decrease) with the amount of the desorbed hydrogen. On the other hand, the mixture of Li4+xMg3(NH2)2-x(NH)4+x + (8-x)LiH (0 ≤ x ≤ 2) is formed and the lattice volume of the Li4+xMg3(NH2)2-x(NH)4+x phase continuously increases with the amount of the desorbed hydrogen in the sloping region on the p-c isotherm.
KW - Crystal structure
KW - Hydrogen storage materials
KW - LiN
KW - MgN
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U2 - 10.1016/j.jallcom.2006.03.044
DO - 10.1016/j.jallcom.2006.03.044
M3 - Article
AN - SCOPUS:33845703128
SN - 0925-8388
VL - 428
SP - 307
EP - 311
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
IS - 1-2
ER -