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Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films
Published on: January 26, 2016
Secondary relaxation behavior in a strong glass
1Key laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, China.
The Journal of Physical Chemistry. B
|July 9, 2008
Summary
Strong germanium dioxide glass exhibits unique enthalpy relaxation, where secondary relaxations fully contribute to the primary process. This behavior, characteristic of strong glasses, differs significantly from fragile glass systems.
Area of Science:
- Materials Science
- Solid State Physics
- Glass Science
Background:
- Understanding glass relaxation dynamics is crucial for predicting material properties.
- Hyperquenched Germanium Dioxide (HQGeO2) is a strong glass system with unique relaxation behaviors.
- Fragile glasses exhibit distinct relaxation patterns compared to strong glasses.
Purpose of the Study:
- To investigate the enthalpy relaxation behavior of hyperquenched GeO2 (HQGeO2) glass.
- To analyze the contribution of secondary relaxation units to primary relaxation in strong glasses.
- To identify and characterize Johari-Goldstein (JG) relaxation features in HQGeO2 glass.
Main Methods:
- Hyperquenching-annealing-calorimetry approach was employed.
- Dynamic properties of secondary relaxation were analyzed.
- Comparison with empirical relations for JG relaxation and characteristic relaxation times.
Main Results:
- Unlike fragile glasses, all secondary relaxation units in HQGeO2 contribute to primary relaxation.
- Two key features of Johari-Goldstein relaxation were identified in HQGeO2 glass.
- The characteristic relaxation time at the glass transition temperature (Tg) is approximately 10 s, larger than in fragile glasses.
Conclusions:
- The study verifies that the Johari-Goldstein (JG) relaxation peak is obscured by the alpha peak in dielectric loss curves for strong glasses.
- The findings highlight the distinct relaxation mechanisms in strong glass systems like HQGeO2.
- Quantitative agreement with empirical JG relaxation relations supports the observed behavior.
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