Vibrational Anomalies in Inorganic Glass Formers

Krause, J. T.; Kurkjian, Charles R.

doi:10.1111/j.1151-2916.1968.tb11880.x

Cited by 120 publications

(30 citation statements)

References 8 publications

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“…Similarity of the medium-range order (MRO) of ZnP 2 O 6 glass and v-SiO 2 was confirmed by RMC simulations [16]. Anomalous temperature dependencies of properties of v-SiO 2 are similar with those of zinc metaphosphate glass (thermal expansion, acoustic absorption, sound velocity) [26,27]. The formation of ZnO 6 octahedra [8] alters the silica-like network for ZnO content less than 50 mol%.…”

Section: Zn-o Distances Superpose With P-o and O-o Peaksmentioning

confidence: 75%

“…Our strategy to minimize also the O T sites having no Zn neighbor and short Zn-Zn distances seems us reasonable to realize a silica-like structure for Zn metaphosphate glass. This structure would explain the silica-like temperature anomalies of properties of this glass [26,27]. Moreover, O T sites without modifier neighbor are not known in structures of any phosphate crystals except of the P 2 O 5 forms.…”

Section: Discussionmentioning

confidence: 97%

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Structure of zinc phosphate glasses probed by neutron and X-ray diffraction of high resolving power and by reverse Monte Carlo simulations

Hoppe

Walter

Carl

et al. 2005

Journal of Non-Crystalline Solids

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Section: Zn-o Distances Superpose With P-o and O-o Peaksmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 97%

Structure of zinc phosphate glasses probed by neutron and X-ray diffraction of high resolving power and by reverse Monte Carlo simulations

Hoppe

Walter

Carl

et al. 2005

Journal of Non-Crystalline Solids

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“…On the other hand, the usual anharmonic effects also become more significant at a higher T leading to a turn-over in the temperatrure dependence of α, as circumstantially supported by the old data on several materials cited in Ref. (Krause and Kurkjian, 1968). However, in order to assess this "cross-over" temperature, one needs to know the magnitude of the regular thermal expansion due to the non-linearities of the lattice.…”

Section: Effect)mentioning

confidence: 99%

The Microscopic Quantum Theory of Low Temperature Amorphous Solids

Lubchenko¹,

Wolynes²

2007

Advances in Chemical Physics

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The quantum excitations in glasses have long presented a set of puzzles for condensed matter physicists. A common view is that they are largely disordered analogs of elementary excitations in crystals, supplemented by two level systems which are chemically local entities coming from disorder. A radical revision of this picture argues that the excitations in low temperature glasses are deeply connected to the energy landscape of the glass when it vitrifies: the excitations are not low excited states built on a single ground state but locally defined resonances, high in the energy spectrum of a solid. According to a semiclassical analysis, the two level systems involve resonant collective tunneling motions of around two hundred molecular units which are relics of the mosaic of cooperative motions at the glass transition temperature Tg. The density of states of the TLS is determined by Tg and the mosaic's length scale, which is a weak function of the cooling rate. The universality of phonon scattering in insulating glasses is explained. The Boson Peak and the plateau in thermal conductivity, observed at higher temperatures, are also quantitatively understood within the picture as arising from the same cooperative motions, but now accompanied by thermal activation of the mosaic's vibrational modes. The dynamics of some of the local structural transitions have significant quantum corrections to the semiclassical picture. These corrections lead to a deviation of the heat capacity and conductivity from the standard tunneling model results and explain the anomalous time dependence of the heat capacity. Interaction between tunneling centers contributes to the large and negative value of the Grüneisen parameter often observed in glasses.

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“…25 Using ultrasonic investigation, many studies have been devoted to the influence of the preparation method 26,27 and of the impurity content (for example OH impurities) on the amplitude of this peak. It can be pointed out that such a peak is observed in many glasses.…”

Section: 12mentioning

confidence: 99%

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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Vibrational Anomalies in Inorganic Glass Formers

Cited by 120 publications

References 8 publications

Structure of zinc phosphate glasses probed by neutron and X-ray diffraction of high resolving power and by reverse Monte Carlo simulations

Structure of zinc phosphate glasses probed by neutron and X-ray diffraction of high resolving power and by reverse Monte Carlo simulations

The Microscopic Quantum Theory of Low Temperature Amorphous Solids

Dynamic sound attenuation at hypersonic frequencies in silica glass

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