Electroconvection in an unusual nematic compound with strongly positive dielectric anisotropy and negative anisotropy of the conductivity is investigated. For homeotropic alignment, where one has a direct transition to rolls or squares depending on the frequency of the applied voltage, we present a quantitative theory. From the comparison we infer values for some viscosities, which are rather unusual, but not unreasonable in view of the vicinity of the nematic-smectic transition. For planar alignment, electroconvection sets in above a splay Freedericksz transition with "parallel rolls," which is also captured by the theory.
(4-(4 -octylobiphenyl)carboxylane) 4-(2-methylobuthyl) phenol, the substance showing complex polymorphism, has been investigated using the calorimetric, microscopic and X-ray methods. This substance exhibited polymorphism during heating and cooling: a few smectic phases, a cholesteric phase and a blue phase as well. However, the substance polymorphism depends on the rate of heat flow. Existing of the blue phase has been confirmed by polarizing microscopic observations done at several temperature rates.
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