Dielectric hysteresis, relaxation dynamics, and nonvolatile memory effect in carbon nanotube dispersed liquid crystal

被引:56
作者
Basu, Rajratan [1 ]
Iannacchione, Germano S. [1 ]
机构
[1] Worcester Polytech Inst, Dept Phys, Order Disorder Phenomena Lab, Worcester, MA 01609 USA
关键词
carbon nanotubes; dielectric hysteresis; dielectric polarisation; dielectric relaxation; electric domains; electric field effects; electromechanical effects; ferroelectric switching; molecular orientation; nematic liquid crystals; random-access storage; self-assembly; CAPACITANCE BRIDGE; ALIGNMENT;
D O I
10.1063/1.3272080
中图分类号
O59 [应用物理学];
学科分类号
摘要
Self-organizing nematic liquid crystals (LCs) impart their orientational order onto dispersed carbon nanotubes (CNTs) and obtain CNT-self-assembly on a macroscopic dimension. The nanotube-long axis, being coupled to the nematic director, enables orientational manipulation via the LC nematic reorientation. Electric-field-induced director rotation of a nematic LC+CNT system is of potential interest due to its possible application as a nanoelectromechanical system. Electric field and temperature dependence of dielectric properties of a LC+CNT composite system have been investigated to understand the principles governing CNT assembly mediated by the LC. In the LC+CNT nematic phase, the dielectric relaxation on removing the applied field follows a single-exponential decay, exhibiting a faster decay response than the pure LC above a threshold field. The observed dielectric behaviors on field cycling in the nematic phase for the composite indicates an electromechanical hysteresis effect of the director field due to the LC-CNT anchoring mechanism. Observations in the isotropic phase coherently combine to confirm the presence of anisotropic pseudonematic domains stabilized by the LC-CNT anchoring energy. These polarized domains maintain local directors and respond to external fields, but do not relax back to the original state on switching the field off, showing nonvolatile memory effect.
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页数:6
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