Low-frequency Raman scattering from CdS microcrystals embedded in a germanium dioxide glass matrix

Tanaka, Akinori; Onari, Seiichiro; Arai, Toshihiro

doi:10.1103/physrevb.47.1237

Cited by 205 publications

(130 citation statements)

References 35 publications

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“…It is found that in small spheres there are two types of vibrational modes: a spheroidal or dilatation mode and a torsional or surface mode. The two modes are Raman active [23]. However, emission of sound waves by such vibrational modes is a completely unexplored process.…”

Section: Discussionmentioning

confidence: 99%

On the Distinction between Debye Bosons and Phonons

Köbler¹

2015

Int. J. Thermo

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A method is described that allows one to construct the dispersion of the Debye bosons (sound waves) from the known temperature dependence of the sound velocities. The method simply assumes that the sound velocity measured at temperature T gives the slope of the dispersion relation at excitation energy E = kBT. The associated reduced wave vector is set equal to q/q0 = a0kBT/hvL/T. In this way the dispersion of the Debye bosons can be constructed for all thermal energies for which sound velocities vL/T(T) are known. This can be up to melting temperature. Surprisingly, for metals and for insulators the dispersion of the Debye bosons can continue up to wave vector values of several times the zone boundary. At melting temperature the wavelength of the Debye bosons is of the order of the atomic diameters. The sources of the Debye bosons therefore must have atomic dimensions. Spontaneous generation of Debye bosons by individual atoms is, however, a completely unexplored process. Interactions with the atomistic background of phonons or lattice defects provide damping to the Debye bosons and make the material specific sound velocity vL/T(T) additionally sample and temperature dependent. For practically all solids it is observed that elastic constants and vL/T(T) decrease as a function of increasing temperature. For high energies the dispersion relation of the Debye bosons therefore becomes visibly lower than linear. Interactions between Debye bosons and phonons can modify the dispersion of the acoustic phonons appreciably. Because of their different symmetries the dispersion relations of Debye bosons and acoustic phonons can attract each other. It is observed that for low wave vector values the dispersion of the acoustic phonons can assume the linear wave vector dependence of the Debye bosons. At the end of the linear section a functional crossover to a sine-like function of wave vector occurs.

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Section: Discussionmentioning

confidence: 99%

On the Distinction between Debye Bosons and Phonons

Köbler¹

2015

Int. J. Thermo

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“…Low-frequency bands have been reported for Ag particles embedded in SiO 2 thin films, 29 CdSe nanocrocrystals in glasses, 30 CdS microcrystals, 31,32 MgCr 2 O 4 -MgAl 2 O 4 crystals in glass, 33 and nanosized TiO 2 . 34 Despite the number of publications related to SnO 2 and Raman spectroscopy, however, they have not generally been reported for SnO 2 .…”

Section: Low Frequency Modes Of Sno 2 Nanoparticlesmentioning

confidence: 99%

The complete Raman spectrum of nanometric SnO2 particles

Diéguez

Romano‐Rodríguez

Vilà

et al. 2001

Journal of Applied Physics

733

422

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The complete Raman spectrum of SnO 2 nanoparticles in presented and analyzed. In addition to the ''classical'' modes observed in the rutile structure, two other regions shown Raman activity for nanoparticles. The Raman bands in the low-frequency region are attributed to acoustic modes associated with the vibration of the individual nanoparticle as a whole. The high-frequency region is activated by surface disorder. A detailed analysis of these regions and the changes in the normal modes of SnO 2 are presented as a function nanoparticle size.

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“…Recently, vibration properties of small solid particles have become a current subject of intense controversy [8,9,[20][21][22][23]. A key issue is whether Lamb's theory [24] about the vibrations of a small elastic body with a free boundary condition could be applied to a small particle embedded in a matrix.…”

mentioning

confidence: 99%

Spherical Growth and Surface-Quasifree Vibrations of Si Nanocrystallites in Er-Doped Si Nanostructures

Mei

Siu

et al. 2001

Phys. Rev. Lett.

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Si-based Er-doped Si nanostructures were fabricated for exploring efficient light emission from Er ions and Si nanocrystallites. High-resolution transmission electron microscopy observations reveal that Si nanocrystallites are spherically embedded in the SiO 2 matrix. Energy-dispersive x-ray analysis indicates that the Er centers are distributed at the surfaces of nanocrystallites surrounded by the SiO 2 matrix. Lowfrequency Raman scattering investigation shows that Lamb's theory can be adopted to exactly calculate the surface vibration frequencies from acoustic phonons confined in spherical Si nanocrystallites and the matrix effects are negligible.

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Low-frequency Raman scattering from CdS microcrystals embedded in a germanium dioxide glass matrix

Cited by 205 publications

References 35 publications

On the Distinction between Debye Bosons and Phonons

On the Distinction between Debye Bosons and Phonons

The complete Raman spectrum of nanometric SnO2 particles

Spherical Growth and Surface-Quasifree Vibrations of Si Nanocrystallites in Er-Doped Si Nanostructures

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