Character of Devitrification, Viewed from Enthalpic Paths, of the Vapor-Deposited Ethylbenzene Glasses

Ramos, Sérgio L. L. M.; Oguni, Masaharu; Ishii, Kikujiro; Nakayama, Hideyuki

doi:10.1021/jp203612s

Cited by 90 publications

(135 citation statements)

References 18 publications

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“…Afterwards other substances were shown to form stable glasses by vapor-deposition using different techniques, e.g. indomethacin (DSC [5], WAXS [44], AC-nanocalorimetry [45] and ellipsometry [10]), toluene and ethylbenzene (fast scanning [46] and adiabatic calorimetry [7], light interference [6]), propylbenzene and isopropylbenzene (light interference [47]), and nifedipine, felodipine and phenobarbital (DSC [48]). …”

Section: Two Different Observations Of the Stability Of Vapor-depositmentioning

confidence: 99%

“…For deposition temperatures in the vicinity of 0.85 T g vapordeposited glasses exhibit low enthalpy [5,7,34,46,50], the heat capacity of the glass drops by about 4% [50][51][52][53], high density (1.3% denser for TNB) [10], high mechanical moduli (up to 15% increased) [54,55] and they can resist water uptake [44]. 2D WAXS measurements by Dawson et al.…”

Section: Two Different Observations Of the Stability Of Vapor-depositmentioning

confidence: 99%

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In situ investigation of vapor-deposited glasses of toluene and ethylbenzene via alternating current chip-nanocalorimetry

Ahrenberg

Chua

Whitaker

et al. 2013

The Journal of Chemical Physics

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Vapor-deposited glasses of toluene and ethylbenzene have been characterized by in situ ac chip-nanocalorimetry. The high sensitivity of this method allows the detection of small changes in the heat capacity of nanogram size samples. We observe that vapor-deposited glasses have up to 4% lower heat capacities than the ordinary glass. The largest heat capacity decrease and the most kinetically stable glasses of toluene and ethylbenzene are observed in a range of deposition temperatures between 0.75 Tg and 0.96 Tg. Compared to larger molecules, deposition rate has a minor influence on the kinetic stability of these glasses. For both toluene and ethylbenzene, the kinetic stability is strongly correlated with the heat capacity decrease for deposition temperatures above 0.8 Tg. In addition, ac-nanocalorimetry was used to follow the isothermal transformation of the stable glasses into the supercooled liquid at temperatures slightly above Tg. Toluene and ethylbenzene stable glasses exhibit a constant transformation rate which is consistent with the growth front mechanism recently demonstrated for tris-naphthylbenzene and indomethacin. The kinetic stability of the most stable toluene and ethylbenzene glasses is comparable to that observed for other stable glasses formed by vapor deposition.

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Section: Two Different Observations Of the Stability Of Vapor-depositmentioning

confidence: 99%

Section: Two Different Observations Of the Stability Of Vapor-depositmentioning

confidence: 99%

In situ investigation of vapor-deposited glasses of toluene and ethylbenzene via alternating current chip-nanocalorimetry

Ahrenberg

Chua

Whitaker

et al. 2013

The Journal of Chemical Physics

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“…This allows molecules to utilize surface mobility and rearrange towards configurations with lower enthalpy [34]. These glasses have properties such as density, elastic modulus, enthalpy and specific heat, which would otherwise be obtained only if ordinary glasses were annealed for thousands of years [33,35,36]. The main focus of this work is to explore the β relaxation in such highly stable glasses.…”

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confidence: 99%

Suppression ofβRelaxation in Vapor-Deposited Ultrastable Glasses

et al. 2015

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“…This limitation has been recently defeated by growing glasses directly from the vapor phase (11, 12). Those glasses, dubbed "ultrastable glasses," can be synthesized by physical vapor deposition in short time scales and show unprecedented thermodynamic and kinetic stability (13)(14)(15)(16)(17). Changing the growth parameters has a strong effect on the properties of the glass.…”

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confidence: 99%

Suppression of tunneling two-level systems in ultrastable glasses of indomethacin

Pérez-Castañeda

Rodríguez-Tinoco

Rodríguez‐Viejo

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

126

116

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Glasses and other noncrystalline solids exhibit thermal and acoustic properties at low temperatures anomalously different from those found in crystalline solids, and with a remarkable degree of universality. Below a few kelvin, these universal properties have been successfully interpreted using the tunneling model, which has enjoyed (almost) unanimous recognition for decades. Here we present low-temperature specific-heat measurements of ultrastable glasses of indomethacin that clearly show the disappearance of the ubiquitous linear contribution traditionally ascribed to the existence of tunneling twolevel systems (TLS). When the ultrastable thin-film sample is thermally converted into a conventional glass, the material recovers a typical amount of TLS. This remarkable suppression of the TLS found in ultrastable glasses of indomethacin is argued to be due to their particular anisotropic and layered character, which strongly influences the dynamical network and may hinder isotropic interactions among low-energy defects, rather than to the thermodynamic stabilization itself. G lasses or amorphous solids are well known (1, 2) to exhibit thermal and acoustic properties very different from those of their crystalline counterparts. Even more strikingly, many of these properties are very similar for any glass, irrespective of the type of material, chemical bonding, etc. Hence the low-temperature properties of noncrystalline solids are said to exhibit a universal "glassy behavior." In particular, below 1−2 K the specific heat of glasses depends approximately linearly on temperature, C p ∝T, and the thermal conductivity almost quadratically, κ ∝ T 2 , in clear contrast with the cubic dependences successfully predicted by Debye theory for crystals. In addition, a broad maximum in C p /T 3 [originated from the so-called "boson peak" in the reduced vibrational density of states g(ω)/ω 2 ] is also typically observed in glasses around 3−10 K, as well as a universal plateau in the thermal conductivity κ(T) in the same temperature range (1, 2).Very soon after the seminal paper by Zeller and Pohl (1) in 1971, Phillips (3) and Anderson et al. (4) independently introduced the well-known standard tunneling model (TM). The fundamental idea of the TM is the ubiquitous existence of atoms or small groups of atoms in amorphous solids due to the intrinsic atomic disorder, which can perform quantum tunneling between two configurations of very similar energy, usually named twolevel systems (TLS). This simple model was able to account for the abovementioned thermal and acoustic anomalies of glasses below 1−2 K, and soon acquired unanimous recognition. Only very few authors (5) posed then criticisms against the standard TM, pointing out how improbable it was that a random ensemble of independent tunneling states would produce essentially the same universal constant for the thermal conductivity or the acoustic attenuation in any substance. Indeed, significant discrepancies with the TM below ∼100 mK have also been reported (6-9), in particular ...

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Character of Devitrification, Viewed from Enthalpic Paths, of the Vapor-Deposited Ethylbenzene Glasses

Cited by 90 publications

References 18 publications

In situ investigation of vapor-deposited glasses of toluene and ethylbenzene via alternating current chip-nanocalorimetry

In situ investigation of vapor-deposited glasses of toluene and ethylbenzene via alternating current chip-nanocalorimetry

Suppression ofβRelaxation in Vapor-Deposited Ultrastable Glasses

Suppression of tunneling two-level systems in ultrastable glasses of indomethacin

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