Low temperature thermal properties and intrinsic defects in vitreous silica

Löhneysen, H. v.; Platte, Michael

doi:10.1007/bf01320211

Cited by 28 publications

(8 citation statements)

References 31 publications

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“…The densities of defect states are nsc h = 2.1 x 10 t8 cm -3 and 9.1 x 10tVcm -3 for n-SW and c-SW, respectively. A/ks is comparable with the value determined earlier [25] for n-SW, while the values for nsch differ somewhat because of the difficulty to determine C' reliably at higher temperatures. For n-SW, nsch corresponds to a defect concentration of 32 ppm, much lower than the concentration of C1-.…”

Section: Resultssupporting

confidence: 82%

“…As has been observed in uncompacted a-SiO2 and other glasses, the specific heat below 0.3 K can be more adequately described by a power law C ~ T" with n > 1. We find n = 1.33 for c-SW, slightly larger than n = 1.23-1.30 [23,21,25] ofn-SW. For c-SI, a reliable determination of n is not possible because that 10 5 .…”

Section: Resultsmentioning

confidence: 83%

“…This unusual feature which is not included in (1) has the form of a Schottky anomaly, indicating a specific two-level defect [25]. However, there are no particular impurities present in Suprasil W except for 200-400 ppm of C1-which is somewhat more than in, e.g.…”

Section: Resultsmentioning

confidence: 97%

“…2. It has been attributed to a Schottky anomaly of unknown origin [25] and will be discussed in more detail at the end of this section. In the whole temperature range, the specific heat of c-SI is suppressed a little more than that of c-SW, consistent with the slightly higher mass density.…”

Section: Resultsmentioning

confidence: 99%

“…Suprasil I (50-100 ppm). The anomaly is considerably suppressed after electron irradiation [25], but not after heat treatment [21]. After a subtraction of the background specific heat C' (obtained by fifth order polynomial fits indicated by solid lines in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Low-temperature specific heat of compacted vitreous silica

Liu

Löhneysen

Weiß

et al. 1995

Z. Phys. B - Condensed Matter

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We present low-temperature specific-heat measurements of two types of irreversibly compacted vitreous silica (Suprasil W and Suprasil I, differing in their OH-content). In the whole temperature range investigated (0.1 K < T < 35 K), the specific heat C is reduced by up to 50% compared to that of uncompacted samples but exhibits a similar temperature dependence, with the characteristic maximum in C/T 3 shifted to higher temperatures. This coherent change of C, which is roughly the same for both types of vitreous silica, gives strong evidence that the low-energy excitations characteristic of amorphous materials have a common structural origin. Possible relations to the microscopic changes upon compaction are discussed, giving support to the coupledrotation model of SiO4 tetrahedra. Phenomenologically, the change of C upon compaction can be understood by the soft-potential model. The relationship between height and position of the C/T 3 maximum observed in normal and compacted states for both types of vitreous silica and, surprisingly, also for ~-quartz hints at a correlation between the mechanisms leading to the C/T 3 maximum for amorphous and crystalline materials with similar shortrange order.

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Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Low-temperature specific heat of compacted vitreous silica

Liu

Löhneysen

Weiß

et al. 1995

Z. Phys. B - Condensed Matter

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A new theoretical approach to the low‐temperature specific heat of disordered solids

Hüttner

Pompe

1982

Physica Status Solidi (b)

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Starting from a perturbation theory for the free energy of disordered solids, the anomalous temperature dependence of the specific heat can be calculated. The model under consideration is based on the two common features of a large group of disordered solids, firstly, the distorted SRO, and, secondly, the cluster-like arrangement of strongly distorted atoms which are imbedded in a crystallike matrix. The theory yields the increase of the specific heat proportional to T for very low temperatures and the anomalous high value of the P-term. The calculated values coincide very well with the experimentally determined temperature dependence for disordered covalent solids.Ausgehend von einer Storungstheorie fur die freie Energie von ungeordneten Festkorpern kann die anomale Temperaturebhangigkeit der spezifischen Warme berechnet werden. Das vorgeschlagene Modell baut auf zwei Charakteristika auf, die einer groI3en Gruppe von ungeordnehn Festkorpern gemeinsam sinddie gestorte Nahordnung und die clusterartige Anordnung der stark gestorten Atome, die in eine kristallartige Matrix eingebettet sind. Die Theorie beschreibt den Anstieg der spezifischen Warme proportional zu T fur sehr niedrige Temperaturen und den anonial hohen Beitrag des Ts-proportiooalen Terme. Die berechneten Werte stimmen sehr gut mit der experimentell bestimmten Temperaturabhiingigkeit fur ungeordnete kovalente Festkorper uberein.attenuation, and velocity [a, lo]. It is surprising that thermal and acoustic properties of non-crystalline materials, or of those with greatly disturbed crystallinity, depend only weakly on structure and nature of bonding: They are similar in completely different solids (as vitreous SiO,, the amorphous polymer PMMA, or the glassy metal Pd-Si-Cu). I n addition to this, highly disordered crystals may also show part of the behaviour charscteristic of glassy materials a t low temperatures [ I l l .

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Low temperature thermal properties of crystalline quartz after electron irradiation

Hofacker

Löhneysen

1981

Z. Physik B - Condensed Matter

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Low temperature thermal properties and intrinsic defects in vitreous silica

Cited by 28 publications

References 31 publications

Low-temperature specific heat of compacted vitreous silica

Low-temperature specific heat of compacted vitreous silica

A new theoretical approach to the low‐temperature specific heat of disordered solids

Low temperature thermal properties of crystalline quartz after electron irradiation

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