Temperature and Electric Field Dependences of the Local Layer Structure in Anti-Ferroelectric Liquid Crystals Measured by X-Ray Micro-Diffraction

Abstract

The local layer of the antiferroelectric liquid crystal has been investigated as a function of the temperature near the SmA to SmC _A * phase transition by synchrotron X-ray microbeam diffraction. The stripe texture in the SmA phase well above the phase transition temperature is related to the in-plane layer deflection. Just above the phase transition temperature, the clear stripe starts to grow and the local layer structure becomes the combination of the vertical-chevron and the horizontal-chevron. With decreasing temperature in the SmC _A * phase, the chevron angle increases. The growth of the chevron structure is explained by the gradual reduction of the layer spacing. The time resolved measurement of the local layer structure in the electroclinic effect is also carried out to characterize the layer response in the SmA phase. The comparison of the chevron structure between the antiferroelectric and the ferroelectric liquid crystal is made.

Keywords:

• Anti-ferroelectric liquid crystal
• stripe texture
• chevron local layer structure
• electroclinic
• synchrotron X-ray microbeam
• X-ray micro-diffraction

Acknowledgement

The authors would like to thank the staff of PF for their help during experiments. We wish to thank Professor K. Sekizawa, Professor Y. Takano and Dr. K. Takase for their continuous encouragement during the study. This work was carried out under the approval of the Photon Factory Advisory Committee (Proposal No. 98G341 and 00G279). This work was partly supported by Grant-In-Aid for Scientific Research on Priority Area (B) (12129202 and 12129206), the Ministry of Education, Science, Sports and Culture.