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Understanding temperature-modulated calorimetry through studies of a model system
Jean-Luc Garden1, Michel Peyrard2
1University of Grenoble Alpes, CNRS, Grenoble INP, Institut NÉEL, 38000 Grenoble, France.
Physical Review. E
|April 16, 2022
Summary
This study clarifies temperature-modulated calorimetry (TMC) by analyzing a model system. Findings reveal how TMC measures frequency-dependent heat capacity, entropy production, and aging effects in glassy materials.
Area of Science:
- Physical Chemistry
- Materials Science
- Thermodynamics
Background:
- Temperature modulated calorimetry (TMC) is a prevalent technique with unresolved fundamental questions.
- Understanding the nuances of heat capacity and relaxation phenomena in complex systems remains a challenge.
Purpose of the Study:
- To investigate temperature-modulated calorimetry at constant average temperature using a model system.
- To precisely define frequency-dependent heat capacity and its link to entropy production.
- To explore TMC's capability in observing sample aging and the Kovacs effect in out-of-equilibrium systems.
Main Methods:
- Utilized a model system with a nontrivial spectrum of relaxation times.
- Conducted temperature-modulated calorimetry experiments at constant average temperature.
- Compared measurements from standard scanning calorimetry (SSC) and TMC.
Main Results:
- Established the relationship between frequency-dependent heat capacity, entropy production, and aging in glassy samples.
- Demonstrated TMC's ability to observe the Kovacs effect, a memory phenomenon in out-of-equilibrium systems.
- Showcased the complementary nature of SSC and TMC, highlighting distinct features probed by each.
Conclusions:
- TMC provides insights into energy transfer timescales and aging phenomena.
- SSC and TMC are complementary techniques, with SSC detecting relaxations not captured by low-frequency TMC.
- This research enhances the understanding and application of modulated calorimetry in materials science.
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