Hydrogen locations, diffusion and the electronic density of states in yttrium dihydrides: A nuclear magnetic resonance investigation

Anderson, David L.; Barnes, R. G.; Hwang, Taesoon; Peterson, D.T.; Torgeson, D. R.

doi:10.1016/0022-5088(80)90309-4

Cited by 25 publications

(6 citation statements)

References 13 publications

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“…H atoms prefer to occupy the lower energy tetrahedral locations, and it was initially believed that in the dihydride configuration, all the H atoms would be in the tetrahedral sites [21], which when fully loaded would yield Y4H8, which is the stoichiometric ratio YH2. However, it was later shown that octahedral sites are partially occupied before the tetrahedral sites are completely filled at x<2 [22][23][24]. Similar observations were made by Khodosov and Andrievskii [25] in FCC ZrH2.…”

Section: Discussionsupporting

confidence: 73%

“…Although only YH1.87 was studied, hydrogen diffusion in yttrium hydride is also a function of hydrogen concentration, which is correlated to the available occupancy positions of hydrogen as presented earlier in this section. Most of the data available in the literature [13,24,30,31] are focused on higher H concentrations for cases in which there is higher H mobility per the information presented above. To gain a more comprehensive understanding, additional IQNS experiments at BASIS, SNS, are planned to investigate hydrogen concentration dependence on hydrogen diffusion in yttrium hydride as part of the FY2021 efforts.…”

Section: Discussionmentioning

confidence: 99%

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Hydrogen Diffusivity Measurements of YH<sub>1.87</sub> Moderator Material with Incoherent Quasielastic Neutron Scattering

Hu¹,

Cakmak²,

Mamontov³

2020

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Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Hydrogen Diffusivity Measurements of YH<sub>1.87</sub> Moderator Material with Incoherent Quasielastic Neutron Scattering

Hu¹,

Cakmak²,

Mamontov³

2020

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“…As mentioned above, the -phase hydride forms when the tetrahedral sites of the crystal fill with hydrogen, while the -phase hydride forms upon accommodation of further hydrogen into the octahedral sites. However, as noted above, octahedral site occupation has been observed even at room temperature [17], [71].…”

Section: Hydrogen Self-diffusion In Yttrium Hydridesmentioning

confidence: 65%

“…The magnetic properties and the hydrogen self-diffusion properties have been measured using nuclear magnetic resonance (NMR) in the literature [17], [18]. This technique applies a magnetic field to a sample to probe the local magnetic fields about the nucleus of interest.…”

Section: Summary Of Measurement Techniquesmentioning

confidence: 99%

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Advanced Moderator Material Handbook

Shivprasad

Cutler

Jewell

et al. 2020

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High hydrogen density moderators such as metal hydrides are an important research topic within the DOE NE Microreactor Research, Development, and Deployment (RD&D) Program due to their ability to retain hydrogen to much higher temperatures than other hydrogenous media. This class of moderators, which includes yttrium dihydride (YH2), thermalizes neutrons in the system such that the overall fuel mass or the required uranium enrichment in the system can be significantly reduced. Knowledge of material properties, both in the as-fabricated and irradiated state, are important to understanding moderator performance during steady-state and transient reactor operation. Provided in this document is the Advanced Moderator Material Handbook, which provides a detailed summary of the literature data on yttrium dihydride, thermomechanical and other property data, and a critical evaluation of that data. This handbook also provides a description of ongoing experiments to understand in-reactor performance, such as irradiations in ATR, as well as nuclear data from an integral critical experiment at NCERC. The majority of this report focuses on measured values but also includes some modeling results for comparison where applicable.

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Hydrogen Diffusion and Radiationless Electron Transfer in Metal Hydrides

Lupu¹

1989

Physica Status Solidi (b)

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The activation energies of the radiationless electron transfer are calculated from the optical spectra of some Sc, Y, La, Lu, Nb, Pd, and Mg,Ni hydrides. These are practically the same with the values of the activation energies for hydrogen diffusion, pointing out to the importance of electron transfer from localized states to the conduction band in the mechanism of hydrogen diffusion. The exponential temperature dependence of the radiationless electron transfer probability together with vibrational tunneling a t low temperatures can account for the temperature dependence of H diffusion in the entire temperature range. A comparison between the electronic structures of NiH and PdH qualitatively explains the higher activation energy of H diffusion in Xi. Isotopic effects in Pd hydrides and a treatment based on Frenkel defects also support the proposed model. Es werden die Aktivierungsenergien der strahlungslosen Elektroneniibertragung &us den optischenSpektren einiger Sc-, Y-, La-, Lu-, Nb-, Pd-und Mg,Ni-Hydride berechnet. Sie sind praktisch gleich mit den Werten der Aktivierungsenergien der Wasserstoffdiffusion und zeigen die Bedeutung der Elektronenubertragang a m lokslisierten Zustanden in das Leitungsband fur den Mechanismus der Wasscrstoffdiffusion. Die exponentielle Temperaturabhangigkeit der strahlungslosen Elektronenubergangswahrscheinlichkeit zusammen mit den Tunneleffekt bei tiefen Temperaturen -kann fur die Temperaturabhingigkeit der Wasserstoffdiffusion im ganzen Temperaturbereich gelten. Ein Vergleich zwischen den Elektronenstrukturen von NiH und PdH erkliirt qualitativ die hohere Aktivierungsenergie der Wasserstoffdiffusion in Ni. Isotopie-Effekte in Pd-Hydride und die Analyse auf Grund von Frenkeldefekten unterstutzen gleichfalls das vorgeschlagene Modell.

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Hydrogen locations, diffusion and the electronic density of states in yttrium dihydrides: A nuclear magnetic resonance investigation

Cited by 25 publications

References 13 publications

Hydrogen Diffusivity Measurements of YH<sub>1.87</sub> Moderator Material with Incoherent Quasielastic Neutron Scattering

Hydrogen Diffusivity Measurements of YH<sub>1.87</sub> Moderator Material with Incoherent Quasielastic Neutron Scattering

Advanced Moderator Material Handbook

Hydrogen Diffusion and Radiationless Electron Transfer in Metal Hydrides

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