Low temperature thermal properties and intrinsic defects in vitreous silica |
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Authors: | Hilbert v Löhneysen Michael Platte |
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Institution: | (1) 2. Physikalisches Institut, Rheinisch-Westfälische Technische Hochschule Aachen, Templergraben 55, Sonderforschungsbereich 125 Aachen-Jülich-Köln, D-5100 Aachen, Federal Republic of Germany;(2) Centre de Recherches sur les Très Basses Températures, C.N.R.S., Grenoble, France |
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Abstract: | Measurements of the low temperature specific heatC
p
(0.04KT2.4K) and thermal conductivityk (0.5KT20K) of high purity vitreous silica (Suprasil W) in the as-received and electron-irradiated states are reported. In the temperature range where the localized excitations inherent in glasses dominateC
p
(T0.5K) no change is observed upon electron irradiation of up to 1019e– (total dose). An anomalyC around 1.8K is observed inC
p
which is reduced by 40% upon irradiation. However, ask is not affected by electron irradiation, localized excitations as origin forC can be ruled out. The density of paramagnetic centers in the most heavily irradiated sample is 51017cm–3 as obtained from the ESR signal. It has been suggested that these centers have diamagnetic precursors in the unirradiated glass. Our measurements indicate that those defects are not associated with the localized excitations. |
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Keywords: | |
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