OPTICAL STUDY OF PHASE-TRANSFORMATION HYSTERESIS IN P-DI-IODOBENZENE

The polymorphic phase transformation in p-di-iodobenzene, as followed by optical path difference measurements, shows a substantial temperature hysteresis. This hysteresis-on the order of 20°C between the forward and reverse transformations-is surprising in light of previous descriptions of this particular phase transformation. Taken together, the various characteristics of the transformation in this material are more consistent with a nucleation and growth process than with a soft-mode transformation mechanism. © 1979 American Institute of Physics.