Large Electrocaloric Effect in a Dielectric Liquid Possessing a Large Dielectric Anisotropy Near the Isotropic-Nematic Transition.

Qian, Xiao‐Shi; Lu, Sheng‐Guo; Li, Xinyu; Gu, Haiming; Chien, Liang‐Chy; Zhang, Qiming

The recent findings of large electrocaloric effects (ECEs) in ferroelectric polymers and in ferroelectric ceramic thin films have attracted great interest for developing new cooling cycles that are environmental friendly and have the potential to reach better efficiency than the existing vapor-compression approach. Compared with these solid state ECE materials, a dielectric fluid with a large ECE can be more interesting because it may lead to new cooling cycles with simpler structures than these based on solid state ECE materials. Here it is shown that a large ECE can be realized in the liquid crystal (LC) 5CB near its nematic-isotropic (N-I) phase transition. 5CB has a large dielectric anisotropy, which facilitates the electric-field-induced large polarization change. As a result, a large ECE, i.e., an isothermal entropy change of more than 23.6 J kg−1 K−1 is observed just above the N-I transition.

PYROELECTRICITY; LIQUID dielectrics; FERROELECTRIC polymers; FERROELECTRIC ceramics; LIQUID crystals; THIN films

Advanced Functional Materials, 2013, Vol 23, Issue 22, p2894

1616-301X

Academic Journal

10.1002/adfm.201202686