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Title: Low-temperature thermal expansion of amorphous solids

Thesis/Dissertation ·
DOI:https://doi.org/10.2172/6737431· OSTI ID:6737431
 [1]
  1. Univ. of Illinois, Urbana-Champaign, IL (United States)

For most amorphous materials at temperatures below approx. = 1 K, the magnitudes and temperature dependences of specific heat, thermal conductivity and ultrasonic dispersion are qualitatively similar, independent of chemical composition. It has been suggested that thermal expansion also exhibits this universal behavior. The development of a dilatometer capable of resolving sample strains as small as 10-12 has permitted measurement of the linear thermal expansion of various glasses below 1 K. These investigations have demonstrated, however, that the low-temperature thermal expansion coefficient of glasses can be positive, negative, large or small. Analysis of measurements performed on two types of vitreous silica, two amorphous polymers, As2S3 and ZrO2:Y2O3 is presented in the context of the phenomenological tunneling-states model. Consistency in explanation of thermal expansion and ultrasonic behavior is maintained by assuming a broad, weakly energy-dependent distribution of coupling strengths between phonons and the localized excitations thought to be characteristic of the glassy state.

Research Organization:
Univ. of Illinois at Urbana-Champaign, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
DOE Contract Number:
AC02-76ER01198
OSTI ID:
6737431
Report Number(s):
DOE/ER/01198-1390; ON: DE83001128
Resource Relation:
Other Information: Thesis; Related Information: Doctor of Philosophy in Physics
Country of Publication:
United States
Language:
English