Thermal properties of halogen-ethane glassy crystals: Effects of orientational disorder and the role of internal molecular degrees of freedom

Journal Article · Fri Aug 28 04:00:00 EDT 2015 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4929530· OSTI ID:22493586

Vdovichenko, G. A.; Krivchikov, A. I.; Korolyuk, O. A. ^[1]; Pardo, L. C.; Rovira-Esteva, M. ^[2]; Bermejo, F. J. ^[3]; Hassaine, M.; Ramos, M. A. ^[4]

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1. B. Verkin Institute for Low Temperature Physics and Engineering of NAS Ukraine, 47 Lenin Ave., 61103 Kharkov (Ukraine)
2. Grup de Caracterització de Materials, Departament de Física i Enginyeria Nuclear, ETSEIB, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Catalonia (Spain)
3. Instituto de Estructura de la Materia, CSIC, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain)
4. Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Francisco Tomás y Valiente 7, 28049 Madrid (Spain)

The thermal conductivity, specific heat, and specific volume of the orientational glass former 1,1,2-trichloro-1,2,2-trifluoroethane (CCl{sub 2}F–CClF{sub 2}, F-113) have been measured under equilibrium pressure within the low-temperature range, showing thermodynamic anomalies at ca. 120, 72, and 20 K. The results are discussed together with those pertaining to the structurally related 1,1,2,2-tetrachloro-1,2-difluoroethane (CCl{sub 2}F–CCl{sub 2}F, F-112), which also shows anomalies at 130, 90, and 60 K. The rich phase behavior of these compounds can be accounted for by the interplay between several of their degrees of freedom. The arrest of the degrees of freedom corresponding to the internal molecular rotation, responsible for the existence of two energetically distinct isomers, and the overall molecular orientation, source of the characteristic orientational disorder of plastic phases, can explain the anomalies at higher and intermediate temperatures, respectively. The soft-potential model has been used as the framework to describe the thermal properties at low temperatures. We show that the low-temperature anomaly of the compounds corresponds to a secondary relaxation, which can be associated with the appearance of Umklapp processes, i.e., anharmonic phonon-phonon scattering, that dominate thermal transport in that temperature range.

• OSTI ID: 22493586
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 8 Vol. 143; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRYSTALS
DEGREES OF FREEDOM
EQUILIBRIUM
ETHANE
GLASS
HALOGENS
ISOMERS
ORGANIC CHLORINE COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
PHONONS
PLASTICS
POTENTIALS
RELAXATION
ROTATION
SPECIFIC HEAT
THERMAL CONDUCTIVITY
UMKLAPP PROCESSES