Direct lattice imaging of domain boundaries in N-paraffin binary eutectics formed from the vapor phase

Abstract

In the past few years, we have been studying the crystal structures of binary paraffin solids in the continuum of states from the stable solid solution through the eutectoid to the fully fractionated eutectic. While electron diffraction data have been very useful to detect microstructures, direct lattice images are needed to depict domain separation.As an example of an eutectic, C30H62/C40H82 thin films were prepared epitaxially on the (100) cleavage face of KCl substrates kept at room temperature under a vacuum of 10−5 torr using the method described by Ueda and Ashida and in our study of palmitone. The specimens were annealed at 40°C for 2 hours. To enhance the phase contrast of lattice images, no carbon films were evaporated onto the organic crystals. After solvating the KCl substrate in pure water, the thin films were collected on holey-carbon coated copper grids for high-resolution study. The thin crystals were examined with a JEOL JEM-100CX electron microscope at 100 kV, and lattice images were taken on Kodak DEF-5 X-ray films at a direct magnification of 19,000X. A minimum dose system was used to reduce the radiation damage during observation.