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High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Transitions through critical temperatures in nematic liquid crystals
Apala Majumdar1, John Ockendon, Peter Howell
1Department of Mathematical Sciences, University of Bath, Bath BA2 7AY, United Kingdom.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|September 17, 2013
Summary
This study reveals a memory effect in nematic liquid crystals (LCs) below the supercooling temperature. This dynamic behavior, crucial for LC material constants, is independent of heating rate and depends on initial temperature.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Physical Chemistry
Background:
- Nematic liquid crystals (LCs) exhibit critical temperatures governing phase transitions.
- Static models predict distinct supercooling and superheating points for LC stability.
- Dynamic effects, particularly memory phenomena, are less understood in LC phase transitions.
Purpose of the Study:
- To investigate critical nematic liquid crystal (LC) temperatures under dynamic conditions.
- To analyze the influence of biaxiality and temperature-varying control variables on LC phase stability.
- To explore memory effects in the isotropic phase below the supercooling temperature.
Main Methods:
- Developing a theoretical model for nematic liquid crystal (LC) phase transitions.
- Analyzing the impact of a slowly varying, temperature-dependent control variable.
- Comparing predictions from purely uniaxial models with biaxial considerations.
Main Results:
- Biaxiality was found to have a negligible effect on critical temperature estimates within the model.
- Dynamic analysis revealed a memory effect in the isotropic phase below the supercooling temperature.
- This delay in stability loss is independent of the rate of temperature change, depending only on the initial temperature.
Conclusions:
- The dynamic behavior of nematic liquid crystals (LCs) exhibits memory effects not captured by static theories.
- A purely uniaxial model adequately describes the delay estimates for critical LC temperatures.
- The findings offer a pathway to refine estimates for essential LC material constants.
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