Low-temperature thermal and elastoacoustic properties of butanol glasses: Study of position isomerism effects around the boson peak

Abstract

We have concurrently measured the specific heat, the thermal conductivity, and the longitudinal and transverse sound velocities at low temperature of glasses from different isomers of butanol (n-butanol, sec-butanol and isobutanol), as well as the low-temperature specific heat for the crystals of n-butanol, isobutanol and tert-butanol. Whereas the elastic constants both for crystals and glasses are found to be almost independent of the position of the hydrogen bonds, the thermal properties at low temperatures of these glasses at a few kelvin (around the boson peak in the reduced specific heat or around the plateau in the thermal conductivity) are found to vary strongly. Our experiments clearly contradict other works or models claiming a Debye scaling of the boson peak, and hence of the excess low-temperature specific heat of glasses. Data analysis based upon the soft-potential model and its extensions allows us to estimate the Ioffe-Regel limit in these and other alcohol glasses, finding a correlation with the boson-peak position in agreement with that previously reported by other groups.

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

“…54 Since the Debye contribution C D T 3 is calculated in the lowtemperature limit from elasto-acoustic measurements for F-112, this means that only two parameters are needed for the SPM fit at low temperature: C TLS and C sm . 41 The C D coefficient is determined first and, then, the two free parameters C TLS TABLE II. Parameters of the soft potential model obtained from the fits to specific heat and thermal conductivity measurements.…”

Low-temperature properties of monoalcohol glasses and crystals

“…Brillouin scattering measurements at low temperatures for the longitudinal and transverse sound velocities of the different glasses made it possible to determine the Debye phonon-like contribution to the specific heat curves. Complementary thermal conductivity measurements for those butanol glasses, made between 2 K and the glass transition temperatures, has served as the basis of an exhaustive study 27 of the different glasses of the same substance, i.e., butanol, in order to assess the effects of changing the spatial arrangement of atoms and the position of hydrogen bonds in the lattice on the low-temperature thermal and elastoacoustic properties around the universal boson peak feature in the glasses. In brief, we have found that the major thermal properties of butanol glasses at low temperatures vary strongly among the different positional isomers, as the hydrogen bond of the hydroxyl group (OH) appears at a different position in the butanol molecule, in clear contrast to elastic Debye contributions, since both the Debye specific heat of the reference crystals and that of glasses derived from Brillouin scattering measurements remain essentially constant for the different isomers (see Fig.…”

“…We emphasize that a consistent analysis of all the low-temperature thermal properties of the butanol glasses using the soft potential model 28 is possible. 27 …”

Low-Temperature Excess Specific Heat in Oxide Glasses: Comprehensive Study of Thermometrically Observed Boson Peak

“…[5][6][7][8][9] In addition, the BP is observed regardless of the constituents (e.g., inorganic, organic, or metallic glasses), which makes it a universal feature of amorphous matter. [10][11][12] Several theories and models have been proposed to explain the origin of BPs. For example, it may be related to acoustic transverse phonons, heterogeneous elasticity, or the VDOS of the van Hove singularities in crystals.…”