Residual entropy in the zero-temperature limit of toluene glass
The specific heat Cp of toluene, doped with 2 mol% ethanol to avoid rapid crystallization, has been measured in both glass and crystal states, and with special accuracy at low temperatures in the range 1.8−20 K using the thermal relaxation method. By making use of the complementary Cp curves measu...
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| Date: | 2019 |
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| Main Authors: | , , , |
| Format: | Article |
| Language: | English |
| Published: |
Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
2019
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| Series: | Физика низких температур |
| Subjects: | |
| Online Access: | http://dspace.nbuv.gov.ua/handle/123456789/176077 |
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| Journal Title: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Cite this: | Residual entropy in the zero-temperature limit of toluene glass / M. Moratalla, P. Bejarano, J.M. Castilla, M.A. Ramos // Физика низких температур. — 2019. — Т. 45, № 3. — С. 377-383. — Бібліогр.: 42 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| Summary: | The specific heat Cp of toluene, doped with 2 mol% ethanol to avoid rapid crystallization, has been measured
in both glass and crystal states, and with special accuracy at low temperatures in the range 1.8−20 K using the
thermal relaxation method. By making use of the complementary Cp curves measured in the reference crystal
state, we have been able to obtain the entropy curve of the glass and eventually the residual entropy of toluene
glass in the zero-temperature limit, that is found to be 5.1 J/(K⋅mol). This value is clearly lower than others previously reported in the literature, which lack the knowledge of the particular specific-heat behavior of glasses at
low temperatures and hence overestimated the glass residual entropy at zero temperature. In addition, we have
studied in detail such low-temperature “glassy anomalies” in the case of toluene, extending and improving previous measurements. The surprising depletion previously reported of tunneling two-level systems in toluene
glass has been confirmed, though this fact coexists with the presence of a broad peak typical of glasses (the socalled boson peak) in Cp/T³ at 4.5 K. For the toluene crystal, the expected cubic Debye behavior has been found
at lower temperatures. |
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