Localized hydrogen modes in LaNi5Hx

Hempelmann, Rolf; Richter, D.; Eckold, G.; Rush, J. J.; Rowe, J. M.; Montoya, M.

doi:10.1016/0022-5088(84)90430-2

Cited by 51 publications

(17 citation statements)

References 21 publications

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“…The separate vibrational peak at 423 K could not be observed. 22 However, they concluded that their spectra agreed with the previous findings. Our results show that the excitation energy from n ¼ 0 to 1 on the 6i Ã site is 62 meV (Table II), which agrees well with previous findings.…”

Section: Inelastic Neutrons Scatteringcontrasting

confidence: 45%

“…In the direction-independent hydrogen vibration spectra measured for powder samples, 22,[33][34][35] the lowest energy peak in the spectra is located around 60-65 meV. This peak is interpreted as excitation at the La 2 Ni 4 octahedral site.…”

Section: Inelastic Neutrons Scatteringmentioning

confidence: 99%

“…These lattice constants agree well with experimentally measured values. [21][22][23][24][25][26] To calculate total energy of the isolated hydrogen molecule, we place the two hydrogen atoms in a cubic cell with a cell length of 10Å. These total energy calculations were performed at the same cutoff energy.…”

Section: Calculationsmentioning

confidence: 99%

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Hydrogen quantum effects in hydride LaNi5H7

Kaneko

Tezuka

Ogawa

et al. 2011

Journal of Applied Physics

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Energy eigenvalues and wave functions of hydrogen atoms in hydride LaNi 5 H 7 are calculated. First-principles electronic structure calculations are employed to obtain the three-dimensional potential energy structure of each hydrogen site. These quantum effects are not negligibly small in evaluation of enthalpy of formation, an important property of hydrogen storage. Including the temperature effect from hydrogen gas, experimental values are well reproduced. The excitation probability of inelastic neutron scattering is also calculated using the wave functions obtained.

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Section: Inelastic Neutrons Scatteringcontrasting

confidence: 45%

Section: Inelastic Neutrons Scatteringmentioning

confidence: 99%

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Hydrogen quantum effects in hydride LaNi5H7

Kaneko

Tezuka

Ogawa

et al. 2011

Journal of Applied Physics

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“…For space group P6/mmm there are about five possible hydrogen sites namely octahedral 3f and tetrahedral 4h, 6m, 12o and 12n. The 3f and/or 12n sites have been most frequently concluded as the favourable occupation sites [17][18][19][20]. This can be explained by a well known empirical geometric criterion for the interstitial occupation of hydrogen.…”

Section: Application To Rni 5 -H 2 Systems and Discusionmentioning

confidence: 99%

Thermodynamical Modeling of P-C Isotherms for Metal Hydride Materials

Tserolas¹,

Katagiri²,

Onodera³

et al. 2010

Trans. Mat. Res. Soc. Japan

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It is generally accepted that under ordinary conditions adopted for the study of metal-hydrogen (M-H) compounds: a) hydrogen can be described reasonably well as an ideal gas, b) the distribution of hydrogen atoms over the different sites of the lattice can be expressed by the Fermi-Dirac statistics, c) the average hydrogen-hydrogen interaction energy which is a function of the number of H-atoms in the lattice includes all the contributions coming from the electrons and the lattice. By considering all the above approximations we have derived a relation between the pressure of gaseous hydrogen and the number of hydrogen atoms in the bulk. The PCIs were obtained by calculating the standard chemical potential for an ideal gas from statistical mechanics and optimizing the other free parameters from the experimental PCIs data at one temperature. We were able to closely predict the PCIs at other temperatures when they were compared with the experimentally obtained PCIs for various RNi 5 -type hydrogen storage materials.

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“…1): one La atom (atom 1), two Ni I atoms of the first type (atoms 2 and 3), and three Ni II atoms of the second type (atoms 4, 5 and 6). The lattice constants used in our calculation are a o =5.023 Α , c o =3.984 Α [27,28]. The initial embedded cluster (LaNi 5 ) 3 is obtained by repeating the primitive cell twice along the c o direction (right side, Fig.…”

Section: Calculation Modelmentioning

confidence: 99%

First-principles calculation of LaNi₅surface

Zheng¹,

Shao-Jie²

2006

J. Phys.: Conf. Ser.

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Abstract. The spin-polarized, all-electron, ab initio calculations have been performed for the electronic structure of the surface of crystal LaNi 5 using the self-consistent cluster-embedding (SCCE) calculation method. The geometrical surface structure of crystal LaNi 5 and its electronic structure having the lowest ground-state energy are obtained, with the full relaxation of atomic positions along the direction perpendicular to the surface. On the surface of crystal LaNi 5 , the La atom protruded, and the Ni atoms caved in, so the surface becomes uneven which increases the contacting area. The effective volume of the surface layer rises by 9%. The Fermi level of the LaNi 5 surface, which is contributed by mainly Ni 3d electrons, is much higher than that of body LaNi 5 . The valence band is not fully filled. For the first two layers of LaNi 5 surface, there are 1.15 electrons transferred from La to Ni, and the two layers have small opposite spin magnetic moments which shows the paramagnet. All calculated results show that the properties of LaNi 5 surface are significantly different from that of body LaNi 5 , but very similar to that of hydride LaNi 5 H 7 . So the geometrical surface structure of crystal LaNi 5 is in favor of the absorption of hydrogen.

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Localized hydrogen modes in LaNi5Hx

Cited by 51 publications

References 21 publications

Hydrogen quantum effects in hydride LaNi5H7

Hydrogen quantum effects in hydride LaNi5H7

Thermodynamical Modeling of P-C Isotherms for Metal Hydride Materials

First-principles calculation of LaNi₅surface

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Localized hydrogen modes in LaNi5Hx

Cited by 51 publications

References 21 publications

Hydrogen quantum effects in hydride LaNi5H7

Hydrogen quantum effects in hydride LaNi5H7

Thermodynamical Modeling of P-C Isotherms for Metal Hydride Materials

First-principles calculation of LaNi5surface

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First-principles calculation of LaNi₅surface