Thermodynamic properties of small amorphous and crystalline Silica particles at low temperatures
Abt. Supraleitung und Magnetismus, Universität Leipzig, Linnéstrasse 5, 04103
2 Physikalisches Institut, Universität Bayreuth, 95440 Bayreuth, Germany
3 Department of Chemistry and Material Science, Northwestern University, Evanston IL 60208, USA
Published online: 15 March 1999
We have measured the low-temperature (K) specific heat and heat release of small amorphous and crystalline SiO2 particles embedded in Teflon and of Vycor. The temperature and time dependence of these properties have been interpreted in terms of the tunneling model. We found that the particle size influences the density of states of tunneling systems of the composite. The smaller the size of the particles the larger is the density of states of tunneling systems P0. Quartz grains with dimensions in the micrometer range show similar glass-like properties as vitreous silica. In comparison with bulk vitreous silica, Vycor shows a much larger P0 in agreement with the behavior we found for small SiO2 particles. We discuss the implication of our results on the origin of the universal low-temperature properties of glasses.
PACS: 61.43.Fs – Glasses / 65.50.+m – Thermodynamic properties and entropy / 63.50.+x – Vibrational states in disordered systems
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999