Pattern forming instabilities of the nematic smectic-B interface

Free growth properties of the smectic B liquid crystalline phase into the s upercooled nematic have been investigated in quasi-two-dimensional geometry . Different orientation combinations of the two phases have been achieved e xperimentally and the interfacial patterns have been studied and analysed a s a function of undercooling, The angular dependence of the surface tension has been deduced from the shape of the interface in thermal equilibrium. T he experimentally determined surface tension anisotropy has been incorporat ed into computer simulations based on the phase-field model. The simulation s have reproduced qualitatively the rich variety of morphologies (extending from the faceted shape to fully developed dendrites) observed in the exper iments for a given set of undercoolings in three geometries. Anisotropic he at diffusion on the nematic side, relevant to our experimental system has a lso been introduced. Both in the experiments and in the simulations we find that the growth is faster in the lower heat diffusion direction. (C) 2000 Elsevier Science B.V. All rights reserved.