Proposta de um diodo térmico feito de cristal líquido nemático

Abstract

It was believed that the thermal energy (heat) from phonons was considered most often as a waste of energy and, moreover, that hindered information processing. On a trying to give utility for this scenario, the phononics rise as alternative of manipulating heat flux by electronic analogs. Dealing with nanostructured materials we already have analogs to diodes, transistors and memory storage. However, the costs associated to manufacture nanostructured materials are high. In this work, we propose the utilization of liquid-crystalline compounds as an alternative to the manufacturing of a thermal diode. This diode consists a cylindrical capillary tube fulfilled with nematic liquid crystal (LC) 4'-pentyl-4-cyanobiphenyl, also known as 5CB, where its molecules exhibit perpendicular (homeotropic) anchoring in the strong and weak regimes in the inner wall. The magnitude of tube's radius and the energy of the anchoring are such that an escaped radial disclination is formed in the capillary tube, where the molecular axis are on average aligned on the director ^n = ^r cos x(r) + ^z sin x(r), being x(r), a monotonic increasing function, the angle between the director ^n and the (r; ℓ) plane. Due to the anisotropic properties of the liquid crystalline molecule and of the spatial configuration of the escaped radial disclination, this system is thermally anisotropic, allowing the rectification effect, once the thermal conductivity constant of the capillary tube in one direction is different from another. We present computational simulations that sustain this effect for different values of heat flux. We show that the thermal effect rectification achieved is similar to the presented by carbon nanotubes, or greater than the presented by boron nitride nanotubes, in room temperature, depending on the setting of some parameters such as thermal power provided, radius and height of he capillary tube and the anchoring angle