Related Experiment Video
Updated: Mar 23, 2026
10:35
Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
Published on: May 29, 2018
9.3K
Nonlinear dielectric spectroscopy in a fragile plastic crystal
M Michl1, Th Bauer1, P Lunkenheimer1
1Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany.
The Journal of Chemical Physics
|March 24, 2016
Summary
This study reveals that high electric fields alter dielectric properties in plastic crystals due to their complex dynamics and entropy changes. These findings offer insights into the behavior of fragile glassy systems and cooperative molecular motion.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Chemical Physics
Background:
- Plastic crystals exhibit unique glassy dynamics, often described as fragile.
- Understanding dielectric properties is crucial for characterizing molecular interactions and phase transitions.
Purpose of the Study:
- To investigate the nonlinear dielectric properties of a succinonitrile-glutaronitrile plastic crystal mixture.
- To explore the influence of high electric fields on dielectric permittivity and susceptibility.
- To analyze the cooperative molecular dynamics and glass transition behavior.
Main Methods:
- Measurement of complex dielectric permittivity under high electric fields.
- Analysis of the third harmonic component of dielectric susceptibility.
- Comparison with theoretical models of glassy dynamics and cooperative motion.
Main Results:
- Observed field-induced alterations in complex dielectric permittivity, attributed to heterogeneous glassy dynamics and entropy variations.
- Detected a hump-like spectral shape in the third harmonic dielectric susceptibility, consistent with cooperative dynamics models.
- Quantified a strong temperature dependence of the number of correlated molecules (Ncorr) in the fragile plastic crystal.
Conclusions:
- The nonlinear dielectric response in this plastic crystal is influenced by both heterogeneous dynamics and field-induced entropy changes.
- The observed spectral shape supports models involving cooperative molecular dynamics.
- The strong temperature dependence of Ncorr highlights the fragile nature of the glass transition in this system, contrasting with strong plastic crystals.
