SYNCHROTRON TOPOGRAPHY OBSERVATIONS OF A LOW-TEMPERATURE PHASE-TRANSITION IN AN ORGANIC-CRYSTAL

In situ observations have been made, using synchrotron white beam X-ray topography in conjunction with a specially designed liquid nitrogen cold-finger cryostat, of single crystals of p-terphenyl as they undergo a phase transition at ≈130K. The transformation involves a monoclinic to triclinic structural change. Direct observation was made of two kinds of domains in the low temperature phase. The original microstructure of the crystal appeared unperturbed despite the considerable strain which develops during the transition. Comparison is drawn between the X-ray results presented here and those obtained previously using transmission electron microscopy. © 1992, Taylor & Francis Group, LLC. All rights reserved.