Acoustic modes of the phonon dispersion relation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="normal">Nb</mml:mi><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">D</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>alloys

Rowe, J. M.; Vagelatos, N.; Rush, J. J.; Flotow, Howard E.

doi:10.1103/physrevb.12.2959

Cited by 48 publications

(5 citation statements)

References 17 publications

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“…In the absence of any other comparative data we believe these values far to be correct because, as one can see from the experimental evidences, the lattice spectra show an increase in the phonon energies at transition from pure Zr to hydrides and deuterides. This behavior is similar to that of Nb [29] and different from that presented for Pd [30], Mn or Ni [31] where the lattice spectra become softer after hydrogenation. As it was already mentioned, the simple Debye model which for a three-dimensional lattice proposes a GVDS like that defined by (1) cannot offer a good description of the acoustic vibrations in these Zr hydrides and deuterides.…”

Section: Fig 2 Debye Temperatures Vs T Calculated From the Gvds Shsupporting

confidence: 37%

On the High-Frequency Limit of Lattice Vibrations in Zirconium Hydrides and Deuterides

Rădulescu

Padureanu

Rapeanu

et al. 2000

phys. stat. sol. (b)

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Section: Fig 2 Debye Temperatures Vs T Calculated From the Gvds Shsupporting

confidence: 37%

On the High-Frequency Limit of Lattice Vibrations in Zirconium Hydrides and Deuterides

Rădulescu

Padureanu

Rapeanu

et al. 2000

phys. stat. sol. (b)

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“…we show in Fig. 6 Recent measurements of the acoustic modes of the phonon dispersion relations in the cubic ci phase of NbD, alloys (up to x = 0.45) show that despite differences in detail, the general features of the dispersion relations of NbD, and Nb-Mo alloys are similar when differences in lattice parameters are allowed for [7]. However, distinct changes in the shape of the dispersion curves of NbD,,, are not seen in Nb -Mo alloys of similar concentration, implying breakdown of the rigid-band model at high deterium concentrations in the NbD, alloys.…”

mentioning

confidence: 87%

“…In view of the structure results discussed above, these broadenings in the vibrational spectrum can be explained in two ways: a) If the cations in the cc-phase of TMACl are disordered around their C3 axis, the observed type-E vibrations can no longer be described by a plane wave in the crystal. A broadening of the observed resonance line may occur [7]. b) Dynamically disordered molecules can produce a broadening of vibrational lines if the reorientational motions occur in the time scale of' picoseconds.…”

Section: Introductionmentioning

confidence: 96%

Deuteron and Niobium‐93 Magnetic Resonance Study of Niobium Deuterides

Barnes¹,

Roenker²,

Brooker³

1976

Ber Bunsenges Phys Chem

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Ker.i~yutrt~ri~ppo~resonanz Mngnetische Kernresonnnz / Phnsenunn.vandlungen 1 Stoffeigenscliuflen Niobium deuterides in the composition range NbD,,,, -NbD,,,, were investigated by means of deuteron and 93Nb magnetic resonance over the temperature range 4.2-420 K. The 0-a transition, in the temperature range 340-415 K for these compounds, is sharply defined by the extinction of the deuteron quadrupole interaction as well as by the appearance of the central component of the 93Nb spectrum when the cubic a phase is formed. These results are discussed in relation to other determinations of the P-a transition temperature. N o other significant changes in the deuteron magnetic resonance spectrum are observed, down to 4.2 K. at which temperature the quadrupole coupling constants are essentially equal. with an average value, e Z q Q / h = 33.0 kHz. The temperature dependent behavior of the 9'Nb resonance spectrum indicates that the boundary between the a + [3 and P regions of the Nb-H(D) phase diagram must pass between the compositions NbD,,,, and NbDo R Z at 300 K. The NMR observations d o not furnish positive support for the occurrence of the 6 and E phases nor for the occurrence of the cubic y phase, but they are not incompatible with the occurrence of these phases. These observations may reflect an intrinsic insensitivity of the deuteron quadrupole interaction to long range ordering of the deuterium in the lattice. Measurements of the 9."b Knight shift are in close agreement with the shifts obtained in Nb-Mo and Nb-Tc alloys. and suggest that up to this relatively high deuterium content (D/Nb = 0.88) the deuterium continues to yield its electron to the conduction band of the metal.Im Temperaturbereich 4.2 -420 K wurden die Deuteriden von Niob im Zusammensetzungsbereich NbD,,,, -NbD,,,, mittels Deuteronund "'Nb-NMR-Spektroskopie untersucht. Der P-a-Phasenubergang dieser Verbindungen erfolgt im Temperaturbereich 340-41 5 K und wird durch die Ausloschung der Deuteron-Quadrupol-Wechselwirkung, bzw. durch die Erscheinung der y3Nb Resonanz, beim Erreichen der kubischen a-Phase genau definiert. Diese Resultate werden in Verbindung mit anderen Bestimmungen der P-a-Ubergangstemperatur besprochen. Bei Abkiihlung bis 4.2 K. der Temperatur bei der die Quadrupol-Kopplungskonstanten unabhangig von Zusammensetzung praktisch denselben Wert haben ( e 2 q Q / h = 33,O kHz), wurden keine wesentliche Anderungen des NMR-Spektrums beobachtet.Die Temperaturabhangigkeit des "Nb Resonanzspektrums zeigt daD bei 300 K die Grenze zwischen den a + P-und P-Gebieten desNb -H/D)-Phasendiagramms zwischen den Zusammensetzungen NbD,,,, und NbD,,,, Iauft. Die NMR-Beobachtungen besorgen keine positive Unterstiitzung zum Auftreten der 5-und E-Phasen weder zum Auftreten der kubischen y-Phase. Sie sind doch mit dem Existenz dieser Phasen nicht unvereinbar. Diese Beobachtungen wiederspiegeln vielleicht eine wesentliche Unempfindlichkeit der Deuteron-Quadrupol-Wechselwirkung zur weitreichend Gitter-Einordnung des Deuterium. Messungen der 93Nb Knight-shift sti...

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“…Lorentzian, Gaussian, and combination (i.e., pseudo-Voigt) lineshapes were attempted to describe the components of the doublet. In addition, the presence of the multiphonon band on the higher-energy side was modelled by the convolution of the main doublet with the phonon density of states previously measured for Nb [26], which possesses a low-energy peak maximum near 16 meV. From the various fitting procedures, a peak splitting of 4.0 ± 0.3 meV was obtained with a median peak energy of 105.1 meV.…”

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confidence: 99%

Excited-state vibrational tunnel splitting of hydrogen trapped by nitrogen in niobium

et al. 1999

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High-resolution inelastic-neutron-scattering spectra of hydrogen trapped by interstitial nitrogen impurities in NbN 0.007H0.004 have been measured to study the vibrational lineshape of the broad 105 meV feature previously observed for NbN 0.004H0.003. The spectrum measured at 4.2 K exhibits clear evidence of a doublet that disappears at higher temperatures. We interpret this result as the first spectroscopic observation of excited-state tunnel splitting of light-atom (H) vibrations in a solid-state double-well potential. We also show that both the observed excited-state splitting of 4.0 ± 0.3 meV and the previously measured ground-state splitting are well represented by a hardened-harmonic-well potential.

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Acoustic modes of the phonon dispersion relation ofNbDxalloys

Cited by 48 publications

References 17 publications

On the High-Frequency Limit of Lattice Vibrations in Zirconium Hydrides and Deuterides

On the High-Frequency Limit of Lattice Vibrations in Zirconium Hydrides and Deuterides

Deuteron and Niobium‐93 Magnetic Resonance Study of Niobium Deuterides

Excited-state vibrational tunnel splitting of hydrogen trapped by nitrogen in niobium

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