The influence of terminal chain on dielectric dynamics of chiral ferroelectric liquid crystals

• Main Author: 林貴雄
• Other Authors: 傅昭銘
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/87267673884095244262

碩士 === 國立高雄師範大學 === 物理學系 === 92 === This thesis aims to study the molecular dynamics of ferroelectric liquid crystals (FLCs) with different terminal chains. For exploring the dynamics of FLCs under alternating electromagnetic field, high precision LCR meters were applied to measure dielectric relaxation spectroscopy of samples. The measured dielectric spectra were analyzed, being based on dielectric relaxation theory, to discover dynamic behavior of liquid crystal molecules under electromagnetic fields. To analyze the ferroelectric SmC* phases of FLC samples, the Debye term, Cole-Cole term and Ionic conductivity term was formulize for fitting with the experimental dielectric spectra. Being based above analysis, the dielectric relaxation spectra of these FLC samples are attributed to the interplay motion of azimuth and tilt-angle in ferroelectric SmC* phases. Further, analysis on the temperature variation of dielectric spectra has concluded that the relaxation frequency and dielectric strength vary systematically with temperature. In addition, the temperature dependence of spontaneous polarization of FLC samples has been measured, to figure out the influence of terminal chains on the physical properties of FLCs. The experimental results have shown that the spontaneous polarizations are correlated with the number of carbon in terminal chains of FLCs. Concluding, the number of carbon in terminal chains of FLCs are contributed for the spontaneous polarization, dielectric strength and relaxation frequency. The result may implicate for device application of FLCs.