Investigation of the “50 K-transition” in PdH0.73 by γ-ray and neutron diffraction

Blaschko, O.; Klemencic, R.; Weinzierl, P.; Eder, O.J.

doi:10.1016/0038-1098(78)91131-6

Cited by 12 publications

(3 citation statements)

References 7 publications

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“…The stable O-sites and metastable T-sites in the Pd lattice are also predicted by ab initio calculations [30][31][32]. Below T ≈ 50 K, at which tem-perature an anomaly is observed in the resistivity and heat capacity, additional diffraction peaks appear gradually with time, indicating a slow positional ordering of the hydrogen atoms [3,[5][6][7][8][9][10]. A recent heat capacity study attributed the anomaly to a glass transition corresponding to the freezing of the configurational motion of hydrogen, which occurs above a hypothetical orderdisorder transition temperature [33].…”

Section: Introductionmentioning

confidence: 93%

“…Neutron diffraction (ND) experiments have revealed that hydrogen atoms are accommodated at interstitial octahedral (O) sites (1/2, 1/2, 1/2) in the face-centered cubic (fcc) lattice of Pd (see Fig. 1) at ambient temperature [2][3][4][5][6][7][8][9][10][11][12]. At temperatures as high as 300 • C, hydrogen atoms can partially occupy tetrahedral (T) sites (1/4, 1/4, 1/4) [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

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Hydrogen diffusion in bulk and nanocrystalline palladium: A quasielastic neutron scattering study

et al. 2016

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The diffusion dynamics of hydrogen in bulk and nanocrystalline palladium has been examined using quasielastic neutron scattering (QENS). With respect to bulk PdH0.73, two relaxation processes were found. For both processes, the variation of the relaxation times with momentum transfer was well reproduced by a model of jump diffusion between adjacent octahedral sites. Upon cooling the fast relaxation fraction decreases. The result suggests that the slow relaxation corresponds to jumps between the ground states and the fast one between excited states. In nanocrystalline PdH0.47 with a size of 8 nm, we found a new fast diffusion process with a smaller activation energy in addition to the one observed in the bulk sample. The new process could be due to the motion of hydrogen atoms in the subsurface region where the potential energy surface is substantially modified by surface strain/distortion effects. This is the first QENS experiment that probes hydrogen diffusion within Pd nanoparticles.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Hydrogen diffusion in bulk and nanocrystalline palladium: A quasielastic neutron scattering study

et al. 2016

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“…Bulk PdH x undergoes a phase transition from a hydrogen dilute α phase to a concentrated, lattice expanded β phase. In both phases, the H atoms occupy the interstitial octahedral (O) sites (1/2, 1/2, 1/2) in the face-centered cubic (fcc) Pd lattice [27][28][29][30][31][32][33][34][35][36][37] (see Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Vibrational states of atomic hydrogen in bulk and nanocrystalline palladium studied by neutron spectroscopy

et al. 2017

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The vibrational states of hydrogen atoms in bulk and nanocrystalline palladium were examined in a wide energy region 0 ≤ ω ≤ 300 meV using neutron spectroscopy. In bulk PdH 0.73 , the vibrational excitations of H atoms were roughly reproduced by the quantum harmonic oscillator (QHO) model. In PdH 0.42 nanocrystals with a diameter of 8 nm, however, additional vibrational excitations were found at energies above 80 meV. The energies and intensities of the additional states were not explained by QHO but reasonably described as vibrations in a highly anharmonic trumpet-like potential. The additional excitations are attributed to the vibrations of H atoms at tetrahedral sites in the subsurface region stabilized by surface effects. The present work has provided the experimental observation of hydrogen vibration inside metal nanoparticles.

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Phase Diagrams and Statistical Thermodynamics of Binary M-H Systems

2005

The Metal-Hydrogen System

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Investigation of the “50 K-transition” in PdH0.73 by γ-ray and neutron diffraction

Cited by 12 publications

References 7 publications

Hydrogen diffusion in bulk and nanocrystalline palladium: A quasielastic neutron scattering study

Hydrogen diffusion in bulk and nanocrystalline palladium: A quasielastic neutron scattering study

Vibrational states of atomic hydrogen in bulk and nanocrystalline palladium studied by neutron spectroscopy

Phase Diagrams and Statistical Thermodynamics of Binary M-H Systems

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