Abnormal relaxation kinetics in D-mannitol glass confined by nanoporous alumina

Cao, Yaru; Song, Lijian; Li, Ao; Huo, Juntao; Li, Fushan; Xu, Wei; Wang, Junqiang

doi:10.1007/s11433-020-1535-3

Cited by 3 publications

(4 citation statements)

References 25 publications

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“…And the narrower O-H stretching models of the confined samples should be caused by the suppression of hydrogen bonds. [7] The enhanced glass forming ability may be attributed to the suppression of hydrogen bonds, which is consistent with other works. [39][40][41] After confinement, the S * becomes negative, which suggests a relaxation-induced disordering phenomenon.…”

Section: Resultssupporting

confidence: 91%

“…[23] Along with the increase of annealing time, the activation energy gradually increases to about 116 kJ/mol, which is close to the E * of α relaxation. [7] Such a two-step relaxation phenomenon during isothermal annealing have been observed in polymer, basalt glass and metallic glasses. [31][32][33][34][35] For the Au 35 nanoconfined glass, the relaxation barrier is much smaller than the free glass and exhibits similar transition.…”

Section: Resultsmentioning

confidence: 84%

“…The nanoconfined glasses usually exhibit enhanced thermal properties compared to the free glasses, e.g., higher glass transition temperature [1][2][3][4] and depressed crystallization kinetics. [5,6] For molecular glasses, the hydrogen bonds are depressed in nanoconfinement that can significantly improve the stability of small molecular glass, [7] which may be helpful in promoting the applications of amorphous drugs. [8] However, such changes in thermal properties depend on kinds of experimental factors, e.g., nanoporous material, the size of the nanopores or the dimensionality.…”

Section: Introductionmentioning

confidence: 99%

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Small activation entropy bestows high-stability of nanoconfined D-mannitol*

Cao¹,

Song²,

Cao³

et al. 2021

Chinese Phys. B

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It has been a long-standing puzzling problem that some glasses exhibit higher glass transition temperatures (denoting high stability) but lower activation energy for relaxations (denoting low stability). In this paper, the relaxation kinetics of the nanoconfined D-mannitol (DM) glass was studied systematically using a high-precision and high-rate nanocalorimeter. The nanoconfined DM exhibits enhanced thermal stability compared to the free DM. For example, the critical cooling rate for glass formation decreases from 200 K/s to below 1 K/s; the T g increases by about 20 K–50 K. The relaxation kinetics is analyzed based on the absolute reaction rate theory. It is found that, even though the activation energy E* decreases, the activation entropy S* decreases much more for the nanoconfined glass that yields a large activation free energy G* and higher thermal stability. These results suggest that the activation entropy may provide new insights in understanding the abnormal kinetics of nanoconfined glassy systems.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Small activation entropy bestows high-stability of nanoconfined D-mannitol*

Cao¹,

Song²,

Cao³

et al. 2021

Chinese Phys. B

Self Cite

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“…Investigations of dynamic relaxation over different timescales are crucial for understanding the natures of various materials such as glasses. [1][2][3] Nuclear magnetic resonance (NMR) is a unique tool that can characterize the structures and dynamics over a wide range of timescales in solids and liquids. [4][5][6][7] The extension of NMR to a high-temperature range provides a good opportunity to study the details of the structure and dynamics of various materials in liquid states such as silicates, [8,9] oxides, [10] molten salts, [11,12] and metallic liquids.…”

Section: Introductionmentioning

confidence: 99%

High-precision nuclear magnetic resonance probe suitable for in situ studies of high-temperature metallic melts

Li¹,

Xu²,

Chen³

et al. 2022

Chinese Phys. B

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High-temperature nuclear magnetic resonance (NMR) has proven to be very useful for detecting the temperature-induced structural evolution and dynamics in melts. However, the sensitivity and precision of high-temperature NMR probes are limited. Here we report a sensitive and stable high-temperature NMR probe based on laser-heating, suitable for in situ studies of metallic melts, which can work stably at the temperature of up to 2000 K. In our design, a well-designed optical path and the use of a water-cooled copper radio-frequency (RF) coil significantly optimize the signal-to-noise ratio (S/NR) at high temperatures. Additionally, a precise temperature controlling system with an error of less than ±1 K has been designed. After temperature calibration, the temperature measurement error is controlled within ±2 K. As a performance testing, 27Al NMR spectra are measured in Zr-based metallic glass-forming liquid in situ. Results show that the S/NR reaches 45 within 90 s even when the sample's temperature is up to 1500 K and that the isothermal signal drift is better than 0.001 ppm per hour. This high-temperature NMR probe can be used to clarify some highly debated issues about metallic liquids, such as glass transition and liquid-liquid transition.

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