Electroconvection in nematic mixtures of bent-core and calamitic molecules

Nandor Eber ,Shingo Tanaka ,Hideo Takezoe ,Katalin Fodor-Csorba 2,Aniko Vajda 2,Agnes Buka 2

Research Institute for Solid State Physics and Optics, Budapest
Tokyo Institute of Technology
2Research Institute for Solid State Physics and Optics, Budapest

The onset of electroconvection in binary mixtures of a bent-core and a rod-like nematic has been characterized by measuring the threshold voltage Uc and the critical wave number of the pattern in a wide range of frequencies f. In the 'banana' rich mixtures a "conductive-prewavy2-patternless-prewavy1" morphological sequence has been detected with an unusual negative slope of Uc(f) at high frequencies. This latter scenario seems to be related to the bent-core component, as it disappears with increasing the concentration of rod-like molecules. In addition, one of the parameters most relevant for electroconvection, the electrical conductivity, has also been varied by ionic salt doping. It has been found that the above effect of the banana shape molecules on the electroconvection scenarios can be suppressed by the conductivity.

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