Effect of neutron irradiation on the density of low-energy excitations in vitreous silica

Smith, Terrance L.; Anthony, P. J.; Anderson, A. C.

doi:10.1103/physrevb.17.4997

Cited by 88 publications

(14 citation statements)

References 54 publications

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“…The specific heat of c~-quartz [27] is shown as solid curve for comparison experiment was limited to T > 0.2 K. The reduction of C by 40% is larger than that caused by other structural modifications, e.g. applying pressure up to 0.4 GPa in situ [5], annealing [21], or irradiating with fast neutrons [26]. This indicates that the TLS density of states is very sensitive to modifications of the intermediate-range order.…”

Section: Resultsmentioning

confidence: 99%

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: Resultsmentioning

confidence: 99%

Low-temperature specific heat of compacted vitreous silica

Liu

Löhneysen

Weiß

et al. 1995

Z. Phys. B - Condensed Matter

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“…19,20 The dimensionless parameter K in amorphous glass compounds is known to be a universal value of about 10 Ϫ4 , which does not show the sample dependence. [20][21][22] The thermal hopping motion of the 4 f electrons across the potential barrier of Eϭ0.136 eV in Sm 3 Te 4 dies out completely at low temperatures. The tunneling motion of the 4 f electrons among the randomly distributed Sm 2ϩ and Sm 3ϩ ions in Sm 3 Te 4 plays an important role at low temperatures.…”

Section: ͑3͒mentioning

confidence: 99%

Ultrasonic study of the charge-fluctuation compoundSm3Te4

et al. 2000

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We have measured the ultrasonic velocity and attenuation coefficient of the rare-earth chalcogenide Sm 3 Te 4 to examine the valence-fluctuation effect due to the coexistence of Sm 2ϩ and Sm 3ϩ ions in the ratio of 1:2. The ultrasonic dispersion around 120 K indicates that the charge-fluctuation time obeys the activation-type temperature dependence ϭ 0 exp(E/k B T) with a characteristic time 2 0 ϭ2.5ϫ10 Ϫ13 sec and an activation energy Eϭ0.136 eV. The absence of the phase transition due to the charge ordering in Sm 3 Te 4 means a freezing of Sm 2ϩ and Sm 3ϩ ions in random distribution at low temperatures. We find an elastic softening with ln T dependence below 15 K down to a spin glass transition around 1.3 K. This striking behavior is attributed to a two-level system due to the tunneling of 4 f electrons among randomly distributed Sm 2ϩ and Sm 3ϩ ions. This result is similar to the ionic tunneling in amorphous glass compounds. Employing the group-theoretical analysis, we show some aspects of charge-fluctuation modes in Sm 3 Te 4 and a possible mechanism for the charge glass state of Sm 2ϩ and Sm 3ϩ ions.

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“…[16 to IS]) caused by density fluctuations, clusters, and point defects. Matsumoto et al [19] show that it is impossible to explain the thermal conductivity of amorphous polymerson the basis of the modified approach according to [14]. Therefore, an additional strongly frequency-dependent scattering mechanism was introduced.…”

Section: Introductionmentioning

confidence: 98%

“…Using the approaches according to [14], the constant change of thermal conductivity can be understood only if the density of states is weakly energy dependent. Such a statement directly contradicts the interpretation of the thermal conductivity of the untreated materials based on the models [13 to 151.…”

Section: Introductionmentioning

confidence: 99%

Low temperature thermal conductivity of amorphous (Fe, Ni, Co) (P, B, Si) alloys and their change by heat treatment

Pompe

Gaafar

Büttner

et al. 1983

Physica Status Solidi (b)

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The thermal conductivity of amorphous metallic alloys (Fe, Ni, Co)l-, (B, P, Si), is measured in the temperature range 2 to 100 K in the as-produced and heat-treated states. By taking into account the results of Matey and Anderson the influence of the nature of the metalloid and the number of metallic components can be discussed. The change of the thermal conductivity due to a structural relasation caused by 8 heat treatment is very different. I n the whole range of temperature a rise of the phonon thermal conductivity of the Fe-Co-B alloy is obtained, whereas no change is observed for the Fe-B alloy. At low temperature (< 40 K) the thermal conductivity of the Fe-Ni-P-B alloy increases by heat treatment, whereas at higher temperatures a reduction is observed. Additionally the t,hermal conductivity of the recrystallized alloy Fe,B,, is investigated.Die Warmeleitfahigkeit amorpher metallischer Legierungen (Fe, Ni, Co)l --2 (B, P, Si), wird im Temperaturbereich von 2 bis 100 K gemessen. Des weiteren wird die Anderung der Wiirmeleitfahigkeit infolge einer durcli Wiirmebehandlung verursachten Strukturrelaxation untersucht. Durch Einbeziehung der Ergebnisse von Matey und Anderson kann der EinfluS der Metalloidart als auch der Anzahl der metallischen Komponenten diskutiert werden. Die Anderung der Warmeleitfilhigkeit der Phononen durch die Warmebehandlung ist unterschiedlich. Bei der Fe-Co-B-Legierung wird ein Anwachsen der Warmeleitfahigkeit im gesamten Temperaturbereich beobachtet, wahrend bei der Fe-B-Legierung keine ibderiing festgestellt werden konnte. Die Wiirmeleitfahigkeit der Fe-Ni-P-B-Legierung wachst infolge der Warmebehandlung bei tiefen Temperaturen (< 40 K) an, wiihrend bei hoheren Temperaturen eine Reduzierung beobachtet wird. Ergiinzend zu diesen Untersuchungen wird die Wiirmeleitfihigkeit an der rekristallisierten Legierung Fe,,B,, gemessen.

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Effect of neutron irradiation on the density of low-energy excitations in vitreous silica

Cited by 88 publications

References 54 publications

Low-temperature specific heat of compacted vitreous silica

Low-temperature specific heat of compacted vitreous silica

Ultrasonic study of the charge-fluctuation compoundSm3Te4

Low temperature thermal conductivity of amorphous (Fe, Ni, Co) (P, B, Si) alloys and their change by heat treatment

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