场致胆甾相-向列相转变:基于分子场理论的研究  

Cholesteric-nematic Phase Transition Induced by a Magnetic Field:Study Based Upon the Molecular Field Theory

作　　者：张艳君[1] 李静[1] 张志东[1] 

机构地区：[1]河北工业大学理学院,天津300130

出　　处：《液晶与显示》2003年第6期417-420,共4页Chinese Journal of Liquid Crystals and Displays

基　　金：河北省自然科学基金资助项目(No103002)

摘　　要：垂直于液晶胆甾相加磁场可以引起胆甾相 向列相转变,基于分子场理论解释了这一现象。在液晶胆甾相,单体取向分布函数按照指向矢的改变定域化。通过对磁场中单分子取向势求平均得到宏观磁场能量;对分子两体作用势作展开,自由能转换为在连续体理论中所具有的形式,得到了发生转变临界磁场的公式。近似计算了温度对临界磁场的影响。A cholesteric-nematic transition can be induced by a magnetic field which is normal to the pitch of the cholesteric liquid crystals. This phenomenon was explained based upon the molecular field theory. One-body orientational distribution function was localized according to variation of the director. The macroscopic magnetic energy was obtained by averaging the orienting potential of a molecule in the magnetic field. By expanding the molecular pair potential properly, the free energy was converted into the counterpart of the continuum theory. The formula for the critical magnetic field, at which the transition takes place, was obtained. The effect of temperature on the critical magnetic field was calculated approximately.

关 键 词：液晶 胆甾相-向列相转变 临界磁场 分子场理论 向列相结构 磁化率 自由能 

分 类 号：O753.2[理学—晶体学]