On the Properties of the Dielectric Dispersion in Novel Dichiral Ferroelectric Liquid Crystals

• Main Authors: Hsin-Hsuan Huang, 黃馨萱
• Other Authors: C.M.Fu
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/11001110679468894938

碩士 === 國立高雄師範大學 === 物理學系 === 88 === This thesis reports the study on dynamic behavior of the novel dichiral ferroelectric liquid crystals (FLCs). In this study, high precision LCR meter was applied to measure complex dielectric of five FLCs with different dichiral molecules, in function of frequency and temperature. Further, the measured dielectric spectra were analyzed in the framework of Debye theories. As well, properties of spontaneous polarization of the dichiral FLCs were studied, in comparison with the relation parameters of molecular dynamics in the liquid crystal samples. The five FLCs samples can classified into two classes. The first class of FLCs shows a dielectric relaxation at lower frequency regime (400-1000Hz). The dielectric dispersion behavior of the first class FLCs can be well analyzes with the Cole-Cole equation, comprising of cell impedance and free charge contribution. The result implies that the molecules reorient around the long axis of FLCs under alternating electromagnetic fields. While, the other class of FLCs demonstrates a lower frequency dielectric relaxation in company with a higher frequency relaxation occurred at frequency regime of 200k-300kHz. The dielectric dispersion behavior of the FLCs agree with the combinative theory of Cole-Cole and Debye terms, comprising of free charge contribution. The result implies that the molecules not only reorient around the long axis, but also, reorient around the short axis of the FLCs under alternating electromagnetic fields. The results may provide understanding of basic physical properties of the novel dichiral ferroelectric liquid crystals, and furthering for photoelectric applications.