NMR studies of electronic structure and hydrogen diffusion in transition metal hydrides

Bowman, Robert C.

doi:10.1007/bf02354668

Cited by 18 publications

(9 citation statements)

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“…(ref. 28 ). Our data suggest that electron density should be larger around H + than around H − nuclei, provided that the chemical shift is predominantly determined by the chemical shielding effect.…”

Section: Resultsmentioning

confidence: 99%

“…The interaction of a spin-1/2 nucleus (such as 1 H) with its surroundings can be described using the Hamiltonian, H int = H D + H CS + H P + H K + … , which includes the magnetic dipolar interaction, H D ; the chemical shielding effect, H CS ; the paramagnetic spin interaction, H P , and the Knight shift effect, H K (refs 28 , 33 ). The negative δ iso of metallic hydrides is principally ascribed to the Knight shift effect, because of the interaction of nuclear spin with conduction electrons, which introduce an ‘extra’ effective field at the nuclei.…”

Section: Resultsmentioning

confidence: 99%

“…for 1 H (ref. 28 ). Both C12A7:H − and S12A7:H − samples have measurable electrical conductivities because of residual electrons.…”

Section: Resultsmentioning

confidence: 99%

“…These questions frequently arise in connection to the chemical shifts of 1 H nuclear magnetic resonance (NMR) spectroscopy in non-metals, which exhibit values that are typical for H + , for example, ~+5 p.p.m. with respect to tetramethylsilane (TMS)111718, whereas ‘metallic’ hydrides, such as TiH 2 , exhibit large negative shifts28.…”

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Hydride ions in oxide hosts hidden by hydroxide ions

et al. 2014

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The true oxidation state of formally ‘H−’ ions incorporated in an oxide host is frequently discussed in connection with chemical shifts of 1H nuclear magnetic resonance spectroscopy, as they can exhibit values typically attributed to H+. Here we systematically investigate the link between geometrical structure and chemical shift of H− ions in an oxide host, mayenite, with a combination of experimental and ab initio approaches, in an attempt to resolve this issue. We demonstrate that the electron density near the hydrogen nucleus in an OH− ion (formally H+ state) exceeds that in an H− ion. This behaviour is the opposite to that expected from formal valences. We deduce a relationship between the chemical shift of H− and the distance from the H− ion to the coordinating electropositive cation. This relationship is pivotal for resolving H− species that are masked by various states of H+ ions.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…for 1 H (ref. 28 ). Both C12A7:H − and S12A7:H − samples have measurable electrical conductivities because of residual electrons.…”

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Hydride ions in oxide hosts hidden by hydroxide ions

et al. 2014

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“…The a-TiCuD 1 7 results are similar. The "TiD 2 " fraction shows a temperature variation of 17', which reflects both atomic hopping and a temperaturedependent electron-induced relaxation caused by the Jahn-Teller distortion from the room temperature cubic phase [5]. …”

Section: Introductionmentioning

confidence: 99%

Characterization of Amorphous and Crystalline TiCuD_x By Deuteron Magnetic Resonance

et al. 1986

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The structure and dynamics of a-TiCu(D,H) 1 . 7 and a-TiCu(D,H) 1 . 4 have been examined by Fourier transform quadrupole echo DMR line shape and relaxation time measurements at 30.7 MHz. The quadrupole-broadened a-TiCu(D,H)x line widths narrowed appreciably above 300 K because of increased D mobility. Low temperature DMR spectra show that static quadrupolar broadening is larger for amorphous samples than for crystalline samples. Deuteron spin lattice relaxation is attributed to conduction electrons below 200 K and to quadrupolar interactions at higher temperatures where deuteron hopping becomes significant. The spin lattice relaxation times indicate that the deuteron mobility is larger by an order of magnitude in the amorphous material than in the crystalline counterparts. Results are compared with those from proton magnetic resonance in corresponding hydrides.

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Hydrogen absorption by LaCu5 and nuclear magnetic resonance (NMR) studies of hydrogen diffusion in β-LaCu5 hydride

Spada

Bowman

Cantrell

1987

Journal of the Less Common Metals

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NMR studies of electronic structure and hydrogen diffusion in transition metal hydrides

Cited by 18 publications

References 58 publications

Hydride ions in oxide hosts hidden by hydroxide ions

Hydride ions in oxide hosts hidden by hydroxide ions

Characterization of Amorphous and Crystalline TiCuD_x By Deuteron Magnetic Resonance

Hydrogen absorption by LaCu5 and nuclear magnetic resonance (NMR) studies of hydrogen diffusion in β-LaCu5 hydride

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NMR studies of electronic structure and hydrogen diffusion in transition metal hydrides

Cited by 18 publications

References 58 publications

Hydride ions in oxide hosts hidden by hydroxide ions

Hydride ions in oxide hosts hidden by hydroxide ions

Characterization of Amorphous and Crystalline TiCuDx By Deuteron Magnetic Resonance

Hydrogen absorption by LaCu5 and nuclear magnetic resonance (NMR) studies of hydrogen diffusion in β-LaCu5 hydride

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Characterization of Amorphous and Crystalline TiCuD_x By Deuteron Magnetic Resonance