scholarly journals On Structural Rearrangements Near The Glass Transition Temperature in Amorphous Silica

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5235
Author(s):  
Michael I. Ojovan ◽  
Robert F. Tournier
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Liquid Phase ◽  
Amorphous Silica ◽  
Percolation Theory ◽  
Second Order ◽  
Structural Rearrangements ◽  
Liquid Transition ◽  
Percolating Network

The formation of clusters was analyzed in a topologically disordered network of bonds of amorphous silica (SiO2) based on the Angell model of broken bonds termed configurons. It was shown that a fractal-dimensional configuron phase was formed in the amorphous silica above the glass transition temperature Tg. The glass transition was described in terms of the concepts of configuron percolation theory (CPT) using the Kantor-Webman theorem, which states that the rigidity threshold of an elastic percolating network is identical to the percolation threshold. The account of configuron phase formation above Tg showed that (i) the glass transition was similar in nature to the second-order phase transformations within the Ehrenfest classification and that (ii) although being reversible, it occurred differently when heating through the glass–liquid transition to that when cooling down in the liquid phase via vitrification. In contrast to typical second-order transformations, such as the formation of ferromagnetic or superconducting phases when the more ordered phase is located below the transition threshold, the configuron phase was located above it.

Second-order Phase Transition Behavior in a Polymer above the Glass Transition Temperature

2021 ◽  
Author(s):  
Mitsuru Ishikawa ◽  
Taihei Takahashi ◽  
Yu-ichiro Hayashi ◽  
Maya Akashi ◽  
Takayuki Uwada
Keyword(s):  
Phase Transition ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Order Phase Transition ◽  
Second Order ◽  
Critical Slowing Down ◽  
Phase Transition Behavior ◽  
Slowing Down ◽  
Second Order Phase Transition

<p>Glass transition was primarily considered to be not phase transition; however, it has similarity to the second-order phase transition. Recent single-molecule spectroscopy developments have prompted re-investigating glass transition at the microscopic scale, revealing that glass transition includes phenomena similar to second-order phase transition. They are characterized by microscopic collective polymer motion and discontinuous changes in temperature dependent relaxation times, later of which is similar to critical slowing down, within a temperature window that includes the polymer calorimetric glass transition temperature. Considering that collective motion and critical slowing down are accompaniments to critical phenomena, second-order phase transition behavior was identified in polymer glass transition.</p>

Novel fluorine-containing second-order NLO polymers with high glass transition temperature

2003 ◽  
Vol 21 (1-3) ◽  
pp. 61-65 ◽  
Author(s):  
Takami Ushiwata ◽  
Etsuya Okamoto ◽  
Kyoji Komatsu ◽  
Toshikuni Kaino ◽  
Alex K-Y Jen
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Second Order ◽  
High Glass Transition Temperature

scholarly journals Second-order Phase Transition Behavior in a Polymer above the Glass Transition Temperature

2020 ◽  
Author(s):  
Mitsuru Ishikawa ◽  
Taihei Takahashi ◽  
Yu-ichiro Hayashi ◽  
Maya Akashi ◽  
Takayuki Uwada
Keyword(s):  
Phase Transition ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Single Molecule ◽  
Order Phase Transition ◽  
Collective Motion ◽  
Relaxation Times ◽  
Second Order ◽  
Second Order Phase Transition

Glass transition was primarily considered to be not phase transition; instead, regarded as pseudo secondorder phase transition due to its similarity to the ordinary second-order phase transition. Recent single-molecule spectroscopy developments have prompted re-investigating glass transition at the microscopic scale, confirming that the initial classification is correct and revealing that glass transition includes phenomena similar to second-order phase transition. They are characterized by microscopic collective polymer motion and discontinuous changes in temperature dependent relaxation times within a temperature window that includes the polymer calorimetric glass transition temperature. Generally, atom or molecule collective motion and discontinuous changes in physical quantities including relaxation times characterize critical phenomena associated with second-order phase transitions near specific temperatures. Thus, second-order phase transition phenomena are involved in polymer glass transition.

Second-order Phase Transition Behavior in a Polymer above the Glass Transition Temperature

2020 ◽  
Author(s):  
Mitsuru Ishikawa ◽  
Taihei Takahashi ◽  
Yu-ichiro Hayashi ◽  
Maya Akashi ◽  
Takayuki Uwada
Keyword(s):  
Phase Transition ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Order Phase Transition ◽  
Second Order ◽  
Critical Slowing Down ◽  
Phase Transition Behavior ◽  
Slowing Down ◽  
Second Order Phase Transition

<p>Glass transition was primarily considered to be not phase transition; however, it has similarity to the second-order phase transition. Recent single-molecule spectroscopy developments have prompted re-investigating glass transition at the microscopic scale, revealing that glass transition includes phenomena similar to second-order phase transition. They are characterized by microscopic collective polymer motion and discontinuous changes in temperature dependent relaxation times, later of which is similar to critical slowing down, within a temperature window that includes the polymer calorimetric glass transition temperature. Considering that collective motion and critical slowing down are accompaniments to critical phenomena, second-order phase transition behavior was identified in polymer glass transition.</p>

scholarly journals Second-order Phase Transition Behavior in a Polymer above the Glass Transition Temperature

2020 ◽  
Author(s):  
Mitsuru Ishikawa ◽  
Taihei Takahashi ◽  
Yu-ichiro Hayashi ◽  
Maya Akashi ◽  
Takayuki Uwada
Keyword(s):  
Phase Transition ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Single Molecule ◽  
Order Phase Transition ◽  
Collective Motion ◽  
Relaxation Times ◽  
Second Order ◽  
Second Order Phase Transition

Glass transition was primarily considered to be not phase transition; instead, regarded as pseudo secondorder phase transition due to its similarity to the ordinary second-order phase transition. Recent single-molecule spectroscopy developments have prompted re-investigating glass transition at the microscopic scale, confirming that the initial classification is correct and revealing that glass transition includes phenomena similar to second-order phase transition. They are characterized by microscopic collective polymer motion and discontinuous changes in temperature dependent relaxation times within a temperature window that includes the polymer calorimetric glass transition temperature. Generally, atom or molecule collective motion and discontinuous changes in physical quantities including relaxation times characterize critical phenomena associated with second-order phase transitions near specific temperatures. Thus, second-order phase transition phenomena are involved in polymer glass transition.

scholarly journals Glasses denser than the supercooled liquid

2021 ◽  
Vol 118 (31) ◽  
pp. e2100738118
Author(s):  
Yi Jin ◽  
Aixi Zhang ◽  
Sarah E. Wolf ◽  
Shivajee Govind ◽  
Alex R. Moore ◽  
...  
Keyword(s):  
Thin Films ◽  
Glass Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Liquid Phase ◽  
Supercooled Liquid ◽  
Kauzmann Temperature ◽  
Crystal Density ◽  
Stable Glasses

When aged below the glass transition temperature, Tg, the density of a glass cannot exceed that of the metastable supercooled liquid (SCL) state, unless crystals are nucleated. The only exception is when another polyamorphic SCL state exists, with a density higher than that of the ordinary SCL. Experimentally, such polyamorphic states and their corresponding liquid–liquid phase transitions have only been observed in network-forming systems or those with polymorphic crystalline states. In otherwise simple liquids, such phase transitions have not been observed, either in aged or vapor-deposited stable glasses, even near the Kauzmann temperature. Here, we report that the density of thin vapor-deposited films of N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD) can exceed their corresponding SCL density by as much as 3.5% and can even exceed the crystal density under certain deposition conditions. We identify a previously unidentified high-density supercooled liquid (HD-SCL) phase with a liquid–liquid phase transition temperature (TLL) ∼35 K below the nominal glass transition temperature of the ordinary SCL. The HD-SCL state is observed in glasses deposited in the thickness range of 25 to 55 nm, where thin films of the ordinary SCL have exceptionally enhanced surface mobility with large mobility gradients. The enhanced mobility enables vapor-deposited thin films to overcome kinetic barriers for relaxation and access the HD-SCL state. The HD-SCL state is only thermodynamically favored in thin films and transforms rapidly to the ordinary SCL when the vapor deposition is continued to form films with thicknesses more than 60 nm.

scholarly journals Second-order Phase Transition Behavior in a Polymer above the Glass Transition Temperature

2020 ◽  
Author(s):  
Mitsuru Ishikawa ◽  
Taihei Takahashi ◽  
Yu-ichiro Hayashi ◽  
Maya Akashi ◽  
Takayuki Uwada
Keyword(s):  
Phase Transition ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Order Phase Transition ◽  
Second Order ◽  
Critical Slowing Down ◽  
Phase Transition Behavior ◽  
Slowing Down ◽  
Second Order Phase Transition

<p>Glass transition was primarily considered to be not phase transition; however, it has similarity to the second-order phase transition. Recent single-molecule spectroscopy developments have prompted re-investigating glass transition at the microscopic scale, revealing that glass transition includes phenomena similar to second-order phase transition. They are characterized by microscopic collective polymer motion and discontinuous changes in temperature dependent relaxation times, later of which is similar to critical slowing down, within a temperature window that includes the polymer calorimetric glass transition temperature. Considering that collective motion and critical slowing down are accompaniments to critical phenomena, second-order phase transition behavior was identified in polymer glass transition.</p>

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