Thermally Stimulated Depolarization Current in Nematic Liquid Crystals

• Main Authors: Chen, Po-Wei, 陳柏偉
• Other Authors: Lee, Wei
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/77455269006925563239

碩士 === 國立交通大學 === 光電系統研究所 === 102 === 　　Thermally stimulated depolarization current technique is a fundamental method for the investigation of microscopic dielectric characteristics of dielectric materials. In this technique, when a system is applied with a DC voltage source, the energy can be stored in the forms of molecular dipoles, free charges, bonds and reorientation of polar fragments. Normally, as the field being released, the stored energy dissipates, and the system relaxes to its original state. With proper treatment, one can release the energy in the form of electrical current and extract useful information. Based on the measurement of the TSDC, in this study, the mechanism of obtaining phase transition temperatures of liquid crystals is presented. The behavior of the TSDC signal from a typical nematic cell is investigated with pre-applied voltages, polarization time and heating rate as variables.