The crystal structure of LiND2 and Mg(ND2)2

Sørby, Magnus H.; Nakamura, Yumiko; Brinks, H.W.; Ichikawa, Takayuki; Hino, Satoshi; Fujii, H.; Hauback, Bjørn C.

doi:10.1016/j.jallcom.2006.03.037

Cited by 69 publications

(59 citation statements)

References 19 publications

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“…22 Here, it should be mentioned that the deuterium in the experimental structure found by Sørby et al is for the sake of simplicity and is referred to as hydrogen in the remainder of this article, both in the text and in the tables. When turning to the H-N-H angles, however, there was a notable spread (101-107°) in the experimental study, 21 whereas the angles found in our and Velikokhatnyi et al's 22 models were much more homogeneous (102.5-102.7°and 102.5-102.9°, respectively). All in all, the differences between our calculated and the previously published structural parameters 21,22 are small.…”

Section: Resultscontrasting

confidence: 65%

“…When turning to the H-N-H angles, however, there was a notable spread (101-107°) in the experimental study, 21 whereas the angles found in our and Velikokhatnyi et al's 22 models were much more homogeneous (102.5-102.7°and 102.5-102.9°, respectively). All in all, the differences between our calculated and the previously published structural parameters 21,22 are small. The most notable difference was in the interatomic distances 24 on a number of hydrides showed that different starting points gave significant variations in the size of the calculated lattice constants when the force relaxation criterion is in the order of 0.05 eV/Å (the same as in the present study).…”

Section: Resultscontrasting

confidence: 65%

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Surfaces and Clusters of Mg(NH₂)₂ Studied by Density Functional Theory Calculations

2009

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Mg(NH 2 ) 2 was studied by bulk, slab, and cluster calculations based on density functional theory within the generalized gradient approximation. Mg(NH 2 ) 2 is confirmed to have a tetragonal unit cell belonging to the space group I4 1 /acd. Five different slabs and their corresponding cleavage energies have been calculated. The most stable surface was the (112) surface, supported by low cleavage energy, special symmetry properties, and small structural changes found during ionic relaxation. Comparison of the density of states calculated from bulk, slab, and clusters indicated that occupied states in the band gap of clusters can be one reason why complex hydrides with nanoparticle structure have enhanced kinetics (in addition to the increased surface area). Calculations of the energy change during removal of NH 3 and H 2 showed that it is energetically easier to remove NH 3 than H 2 from Mg(NH 2 ) 2 , confirming a general trend for metal-N-H systems.

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Section: Resultscontrasting

confidence: 65%

Section: Resultscontrasting

confidence: 65%

Surfaces and Clusters of Mg(NH₂)₂ Studied by Density Functional Theory Calculations

2009

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“…82). 23,42 The conventional unit cell of LiNH 2 , with eight formula units, is illustrated in Fig. 1.…”

Section: A Structural and Electronic Propertiesmentioning

confidence: 99%

Native defects in LiNH2: A first-principles study

Wang

et al. 2011

Phys. Rev. B

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Native defects in lithium amide (LiNH 2 ), a promising candidate for hydrogen storage, are investigated by first-principles calculations based on density functional theory. We examine the structural properties and formation energies of H-, Li-, and N-related defects in all possible states. We find that the dominant H-and Li-related defects are in charged states, i.e., negatively charged H vacancy (V H − ), positively charged H interstitial (H i + ), negatively charged Li vacancy (V Li − ), and positively charged Li interstitial (I Li + ). V Li − and I Li + are present in the highest concentration. The positively charged NH 2 vacancy has the lowest formation energy among N-related defects. Furthermore, migration processes of the dominant defects are investigated. V Li − diffuses most rapidly with the lowest migration energy of 0.20 eV. Both formation and migration energies of Li-related dominant defects are found to be lower than those of H-related dominant defects. With an activation energy of 0.72 eV, V Li − is the major diffusive species in LiNH 2 . Our results further indicate that the formation of H i is the bottleneck for H transport.

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“…The amount of the remaining N estimated from the weight loss was around 10% larger than that expected. A deuterated sample was synthesized in a similar way as sample II, but instead LiND 2 [20] was used as a starting material and 7 MPa D 2 (Taiyo Nippon Sanso, >99.8%) for the final heat treatment. A Li-Mg-N-D intermediate phase (sample III) was prepared by heating the deuterated sample at 200 • C in vacuum for 8 h.…”

Section: Synthesis Of Samplesmentioning

confidence: 99%

Dehydrogenation reaction of Li–Mg–N–H systems studied by in situ synchrotron powder X-ray diffraction and powder neutron diffraction

Nakamura

Hino

Ichikawa

et al. 2008

Journal of Alloys and Compounds

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The crystal structure of LiND2 and Mg(ND2)2

Cited by 69 publications

References 19 publications

Surfaces and Clusters of Mg(NH₂)₂ Studied by Density Functional Theory Calculations

Surfaces and Clusters of Mg(NH₂)₂ Studied by Density Functional Theory Calculations

Native defects in LiNH2: A first-principles study

Dehydrogenation reaction of Li–Mg–N–H systems studied by in situ synchrotron powder X-ray diffraction and powder neutron diffraction

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The crystal structure of LiND2 and Mg(ND2)2

Cited by 69 publications

References 19 publications

Surfaces and Clusters of Mg(NH2)2 Studied by Density Functional Theory Calculations

Surfaces and Clusters of Mg(NH2)2 Studied by Density Functional Theory Calculations

Native defects in LiNH2: A first-principles study

Dehydrogenation reaction of Li–Mg–N–H systems studied by in situ synchrotron powder X-ray diffraction and powder neutron diffraction

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Surfaces and Clusters of Mg(NH₂)₂ Studied by Density Functional Theory Calculations

Surfaces and Clusters of Mg(NH₂)₂ Studied by Density Functional Theory Calculations