Defects 408 transverse dislocations

The textures in homeotropic lamellar phases of lecithin are studied in lecithin-water phases by polarizing microscopy and in dried phases by electron microscopy. In the former, we observe the La phase (the chains are liquid, the polar heads disordered)—the texture displays classical FriedeVs oily streaks, which we interpret as clusters of parallel dislocations whose core is split in two disclinations of opposite sign, with a transversal instability of the confocal domain type. In the latter case, the nature of the lamellar phase is less understood. However, the elementary defects (negative staining) are quenched from the La phase they are dislocations or Grandjean terraces, where the same transversal instability can occur. We also observed dislocations with an extended core these defects seem typical of the phase in the electron microscope. 

In order to understand the rate of alignment, the mobility of defects must be considered. Movement of all defects must be accomplished by climb and glide of edge dislocations at the defect. Examples are shown in Fig. 34. Climb is motion in the layer plane and glide is motion transverse to the layers. Consider a pair of... 

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