X-ray studies of Twist-Grain Boundary A phase of Liquid Crystal

• Main Authors: Yen-Ru Lee, 李彥儒
• Other Authors: Shih-Lin Chang
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/33837389606521669722

碩士 === 國立清華大學 === 物理學系 === 87 === The unusual structures of twist-grain boundary A (TGBA) phase of liquid crystals discovered in 1989, have attracted much attention in recent years. In this study we apply x-ray diffraction technique to investigate the temperature-dependent structural change in the vicinity of the TGBA phase of a series ferroelectric liquid crystals (MD312a), containing oligooxyethylene spacers. It is found that the TGBA phase is formed in the temperature range 53~57℃ and an extra diffraction peak detected at 52.30℃ and 2θ=20°, indicates that fine structural modification takes place near the TGBA phase. Details about the x-ray experimental setup, temperature control ( ΔT~0.01℃ ) and the diffraction data will be presented. The origin of the structural variation will also be discussed.