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Updated: Jun 25, 2026
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High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Simple experimental assessment of smectic translational order parameters.
Nadia Kapernaum1, Frank Giesselmann
1Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
Summary
This study introduces a method to measure the smectic translational order parameter (Sigma) using X-ray scattering. High Sigma values, up to 0.9, were found in various liquid crystals, including de Vries materials.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Crystallography
Background:
- Liquid crystals exhibit complex phase behaviors crucial for display technologies.
- Quantifying the smectic translational order parameter (Sigma) is essential for understanding liquid crystal phases.
- Accurate measurement of Sigma aids in the development of advanced liquid crystal materials.
Purpose of the Study:
- To present a novel procedure for determining the smectic translational order parameter (Sigma).
- To apply this procedure to various liquid crystals, including de Vries and antiferroelectric types.
- To analyze the temperature-dependent intensity of the (001) smectic layer peak using small-angle X-ray scattering (SAXS).
Main Methods:
- Utilizing small-angle X-ray scattering (SAXS) to observe the fundamental (001) smectic layer peak.
- Analyzing the temperature-dependent intensity (I) of this peak to derive the smectic translational order parameter (Sigma).
- Applying the developed procedure to six different liquid crystal samples, including 3M8422 and MHPOBC.
Main Results:
- The developed procedure successfully obtained Sigma values for smectic-A and chiral smectic-A phases.
- Measured Sigma values ranged from 0.5 to 0.9 across the studied liquid crystals.
- The de Vries-type liquid crystal 3M8422 exhibited exceptionally high Sigma values, approximately 0.9.
Conclusions:
- The presented SAXS-based procedure is effective for quantifying the smectic translational order parameter.
- The study highlights significant variations in Sigma values among different liquid crystal types.
- High Sigma values in de Vries materials suggest unique structural ordering properties.
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