EFFECT OF THE I-STAR PHASE TEMPERATURE-RANGE ON THE NATURE OF THE TILTED FLUID TO HEXATIC TRANSITION

High precision layer spacing measurements have been carried out in the C* and I* phases of a number of compounds. The results suggest that the temperature range of the I* phase influences the nature of the tilted fluid to hexatic transition. For smaller ranges of I*, the C* phase evolves continuously to I*. The curves for the temperature variation of the layer spacing indicate that with increasing range of I* one may expect to observe a critical point followed by a line of first-order transitions. The presence of a second hexatic phase, viz., F* below I* also appears to play an important role in determining the nature of the C*-I* transition. A comparison between this scenario and a similar one proposed by Aharony et. al., 1 is also presented. © 1991, Taylor & Francis Group, LLC. All rights reserved.