Lattice dynamics of N<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">D</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>I in the NaCl phase (I) at 296°K

Vagelatos, N.; Rowe, J. M.; Rush, J. J.

doi:10.1103/physrevb.12.4522

Cited by 26 publications

(9 citation statements)

References 42 publications

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“…The results are shown in the inset of figure 1. In the pure compounds reflectivity bands appear close to 100 cm −1 (KI) and 150 cm −1 (ND 4 I), which approximately correspond to the frequencies of the optical phonons at the zone centre (q = 0) [22,23]. The frequencies of the reflectivity bands are in good agreement with published IR results [2,24,25].…”

Section: Resultssupporting

confidence: 86%

“…The phonon energies appear at the same positions as observed by neutron scattering [22,23,26]. We therefore conclude that the third peak results from a breakdown of the selection rules due to disorder, as usually is observed in orientational and dipolar glasses.…”

Section: Resultssupporting

confidence: 78%

“…Optical absorption spectra at room temperature are summarized in [27]. Here minima have been observed approximately at 115 cm −1 for KI, at 150 cm −1 for ND 4 I, at 120 cm −1 for KBr and at 160 cm −1 for NH 4 Br, which coincide well with the phonon energies of the corresponding TO-phonon modes at the zone centre as detected in inelastic neutron-scattering spectroscopy [22,23,26]. These modes characterize a sublattice motion of the ions K + ↔ I − , NH 4 + ↔ I − , K + ↔ Br − and NH 4 + ↔ Br − corresponding to the displacement of the TO modes.…”

Section: Resultssupporting

confidence: 54%

“…The reflectivity of NH 4 Br has already been studied [2] in the β-phase and the TO mode was located at about 160 cm −1 . In addition, the complete dispersion relations for KI [22], KBr [26] and ND 4 I [23] were measured by inelastic neutron scattering. Optical absorption spectra at room temperature are summarized in [27].…”

Section: Resultsmentioning

confidence: 99%

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Lattice vibrations in the mixed crystals (NH₄I)_0.3(KI)_0.7, (ND₄I)_0.3(KI)_0.7and (NH₄Br)_0.3(KBr)_0.7

Ohl

Mayr

Reehuis

et al. 2001

J. Phys.: Condens. Matter

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Transverse optical phonons have been studied in (NH 4 I) 0.3 (KI) 0.7 , (ND 4 I) 0.3 (KI) 0.7 and (NH 4 Br) 0.3 (KBr) 0.7 using Fourier-transform infrared techniques. In all materials three phonon modes have been observed in the far-infrared regime and were followed as a function of temperature in detail. While the first low-frequency mode characterizes a sublattice motion of the alkali ions against the halogenides K + ↔ I − and K + ↔ Br − , the second mode involves vibrations of the ammonium molecules against the halogenide ions NH 4 + ↔ I − , ND 4 + ↔ I − and HH 4 + ↔ Br − . Despite the fact that the average symmetry of these crystals is cubic, the transitional and orientational disorder locally breaks the cubic symmetry, the infra-red selection rules are relaxed and, hence, a third phonon contribution appears. Deviations of the temperature dependence of the eigenfrequencies, as expected for anharmonic modes, are interpreted in terms of a rotation-translation coupling where the phonon modes interact with the orientational degrees of freedom.

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Section: Resultssupporting

confidence: 86%

Section: Resultssupporting

confidence: 78%

Section: Resultssupporting

confidence: 54%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Lattice vibrations in the mixed crystals (NH₄I)_0.3(KI)_0.7, (ND₄I)_0.3(KI)_0.7and (NH₄Br)_0.3(KBr)_0.7

Ohl

Mayr

Reehuis

et al. 2001

J. Phys.: Condens. Matter

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show abstract

“…However, having overcome these difficulties one stands the chance of obtaining information which is unique and extremely detailed in nature. Successful experiments have been carried out on inorganic crystals (Smith et al 1969;Vagelatos et al 1975), molecular crystals (Chaplot 1983), metal-hydrogen systems (Springer 1978) and polymers (King 1974). As an example, we show the dispersion curve for polyethylene measured by Feldkamp et al (1968) ( figure 7).…”

Section: Molecular Crystals Polymers Through Coherent Inelastic Scatmentioning

confidence: 99%

Investigation of hydrogenous materials using neutrons

Dasannacharya

Goyal

1984

Bull. Mater. Sci.

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Slow neutrons have proved to be a very powerful probe for examining materials in general and hydrogenous materials in particular. In this article we review various neutron scattering techniques which have been utilised to investigate different aspects of a variety of hydrogenous materials. TranslationaUy as well as orientationally disordered materials, ferroelectrics, superconductors, metal-hydrogen systems, polymers and biological molecules have been chosen as illustrative examples.

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Other Cubic Crystals (Rock Salt Structure)

Bilz

Kress

1979

Springer Series in Solid-State Sciences

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Lattice dynamics of ND4I in the NaCl phase (I) at 296°K

Cited by 26 publications

References 42 publications

Lattice vibrations in the mixed crystals (NH₄I)_0.3(KI)_0.7, (ND₄I)_0.3(KI)_0.7and (NH₄Br)_0.3(KBr)_0.7

Lattice vibrations in the mixed crystals (NH₄I)_0.3(KI)_0.7, (ND₄I)_0.3(KI)_0.7and (NH₄Br)_0.3(KBr)_0.7

Investigation of hydrogenous materials using neutrons

Other Cubic Crystals (Rock Salt Structure)

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Lattice dynamics of ND4I in the NaCl phase (I) at 296°K

Cited by 26 publications

References 42 publications

Lattice vibrations in the mixed crystals (NH4I)0.3(KI)0.7, (ND4I)0.3(KI)0.7and (NH4Br)0.3(KBr)0.7

Lattice vibrations in the mixed crystals (NH4I)0.3(KI)0.7, (ND4I)0.3(KI)0.7and (NH4Br)0.3(KBr)0.7

Investigation of hydrogenous materials using neutrons

Other Cubic Crystals (Rock Salt Structure)

Contact Info

Product

Resources

About

Lattice vibrations in the mixed crystals (NH₄I)_0.3(KI)_0.7, (ND₄I)_0.3(KI)_0.7and (NH₄Br)_0.3(KBr)_0.7

Lattice vibrations in the mixed crystals (NH₄I)_0.3(KI)_0.7, (ND₄I)_0.3(KI)_0.7and (NH₄Br)_0.3(KBr)_0.7