Elastic properties of a-SiO
                    <sub>2</sub>
                    up to 2300 K from Brillouin scattering measurements

Polian, A.; Vo-Thanh, Dung; Richet, Pascal

doi:10.1209/epl/i2002-00470-4

Cited by 129 publications

(98 citation statements)

References 18 publications

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“…The data of Fig. 2b are close to previous determination of the literature in several commercial silica samples, 21,22,23 and the high temperature part of those curves will be also discussed, in comparison with previous determinations, in another article (Ref. 24).…”

Section: 12supporting

confidence: 88%

Dynamic sound attenuation at hypersonic frequencies in silica glass

2006

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In order to clarify the origin of the dominant processes responsible for the acoustic attenuation of phonons, which is a much debatted topic, we present Brillouin scattering experiments in various silica glasses of different OH impurities content. A large temperature range, from 5 to 1500 K is investigated, up to the glass transition temperature. Comparison of the hypersonic wave attenuation in various samples allows to identify two different processes. The first one induces a low temperature peak related to relaxational processes; it is strongly sensitive to the extrinsic defects. The second, dominant in the high temperature range, is weakly dependent on the impurities and can be ascribed to anharmonic interactions. The origin of sound attenuation in glasses has been a highly debated topic in recent years. Several models have been proposed but no consensus about the interpretation of sound attenuation has been reached. 1,2,3Several mechanisms responsible for sound attenuation have been identified for over the year:1. interactions of acoustic waves with defects characteristic of the disorder. Those defects are often described as tunneling systems responsible for many anomalous properties of glasses in the low temperature regime. 2. thermally activated relaxational processes, as clearly demonstrated by ultrasonic measurements. 5 The microscopic structural origin of the thermally activated processes is often related to tunneling defects or soft modes responsible for the interaction with acoustic waves. 3. Rayleigh-like scattering by static inhomogeneities, independent of temperature. This has been observed for example in porous glasses (xerogels, aerogels). 7,8 This mechanism yield an attenuation varying like q 4 , where q is the momentum transfer of the interaction in scattering experiment. Rayleigh-like scattering has been also put forward to explain the change of regime for the attenuation in the THz range.3,9 An alternative explanation of the frequency power dependence in ω 4 (where ω = 2π/ν is the pulsation of the excitation) in terms of fractons 10 has been also proposed.4. anharmonicity responsible for the interactions of acoustic waves with thermal phonons, as in crystals. 11,12Each mechanism dominates in different temperature and frequency ranges. It is expected that the mechanisms 1 and 2 are dominant at low temperatures, 3 in very inhomogeneous media or at wavelengths comparable to a few atomic length and the mechanism 4 at high temperature and high frequencies. Moreover, the influence of several parameters have been studied in order to distinguish between universal behavior of the sound attenuation in glasses and more specific properties, related for example to composition effects, or to the method of preparation (impurity concentration or thermal history).13 The influence of pressure, 14 irradiation by neutrons 15,16 or permanent densification 9 has also been investigated.In this paper we present results about Brillouin scattering measurements of sound attenuation at hypersonic frequencies in silica. ...

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Section: 12supporting

confidence: 88%

Dynamic sound attenuation at hypersonic frequencies in silica glass

2006

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“…23 The variation of the sound velocity with temperature is found to be comparable to that determined by means of Brillouin light scattering (BLS). 36 Using the resulting Debye frequency we show that the temperature dependence of the BP in silica does not follow the elastic medium transformation, confirming the observation of Ref. 20.…”

Section: Introductionsupporting

confidence: 83%

Elastic anomalies at terahertz frequencies and excess density of vibrational states in silica glass

2011

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We study the temperature dependence of acousticlike excitations measured by means of inelastic x-ray scattering at terahertz frequencies in silica glass. The apparent sound velocity shows, between 300 and 1600 K, the same temperature variation measured, at lower frequencies, by Brillouin light scattering. On the contrary the vibrations at the boson peak (BP) present a much stronger temperature dependence, as indicated by neutron scattering data. The measured dispersion and damping are used to compute the contribution to the vibrational density of states (VDOS) coming from the propagating acousticlike modes. This part of the VDOS accounts only for a fraction of the BP intensity, indicating that other kinds of excitation accumulate in this frequency range. It is consequently not surprising that the BP does not follow the temperature evolution of the Debye frequency, which describes the modification of the continuum medium. Finally we present a comparison between the experimentally accessible quantities and a recently proposed model for the vibrations in glasses, based on the assumption of random spatial variations of the shear modulus [Schirmacher, Europhys. Lett. 73, 892 (2006)].

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“…By comparing the sound speeds in Table I, it is clear that the low-frequency DOS of our models for a-Si and a-SiO 2 are dominated by transverse modes, which is expected due to their degeneracy and lower frequencies compared to the longitudinal modes. The transverse sound speed predicted for our model of a-SiO 2 is 85% of that predicted by the other methods (Table I) and that measured by experiment [63,67,70], which is likely related to the larger density of our samples (see Sec. III A).…”

Section: Sound Speedmentioning

confidence: 46%

“…The smaller values predicted by the structure factors and DOS result from the concavedown dispersion seen at low wave vector (i.e., we are not able to reach the linear portion of the dispersion curve). Experimental measurements of the sound speeds of a-SiO 2 using Brillouin light and inelastic x-ray scattering range between 3800 to 4000 m/s (transverse) and 6000 to 6400 m/s (longitudinal) [63,67,70]. Differences between our predictions and experimental measurements may be related to limitations of the BKS potential.…”

Section: Sound Speedmentioning

confidence: 67%

Thermal conductivity accumulation in amorphous silica and amorphous silicon

2014

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We predict the properties of the propagating and nonpropagating vibrational modes in amorphous silica (a-SiO 2 ) and amorphous silicon (a-Si) and, from them, thermal conductivity accumulation functions. The calculations are performed using molecular dynamics simulations, lattice dynamics calculations, and theoretical models. For a-SiO 2 , the propagating modes contribute negligibly to thermal conductivity (6%), in agreement with the thermal conductivity accumulation measured by Regner et al. [Nat. Commun. 4, 1640]. For a-Si, propagating modes with mean-free paths up to 1 μm contribute 40% of the total thermal conductivity. The predicted contribution to thermal conductivity from nonpropagating modes and the total thermal conductivity for a-Si are in agreement with the measurements of Regner et al. The accumulation in the measurements, however, takes place over a narrower band of mean-free paths (100 nm-1 μm) than that predicted (10 nm-1 μm).

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Elastic properties of a-SiO ₂ up to 2300 K from Brillouin scattering measurements

Cited by 129 publications

References 18 publications

Dynamic sound attenuation at hypersonic frequencies in silica glass

Dynamic sound attenuation at hypersonic frequencies in silica glass

Elastic anomalies at terahertz frequencies and excess density of vibrational states in silica glass

Thermal conductivity accumulation in amorphous silica and amorphous silicon

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Elastic properties of a-SiO 2 up to 2300 K from Brillouin scattering measurements

Cited by 129 publications

References 18 publications

Dynamic sound attenuation at hypersonic frequencies in silica glass

Dynamic sound attenuation at hypersonic frequencies in silica glass

Elastic anomalies at terahertz frequencies and excess density of vibrational states in silica glass

Thermal conductivity accumulation in amorphous silica and amorphous silicon

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Product

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Elastic properties of a-SiO ₂ up to 2300 K from Brillouin scattering measurements