Crystallography of Platelet-Type Hematite Particles by Electron Microscopy

Abstract

Morphology of platelet-type hematite particles (α-Fe₂O₃) produced by the gel-sol method was investigated by both scanning electron microscopy and transmission electron microscopy. In order to determine the orientation of crystal surfaces and make clear structural defects inside the particles, thin samples for transmission electron microscopy were prepared by using an ultra-microtome. The platelet-type particles were found to be single crystals with thickness about 0.2 μm, and most of the particles were bound by {0001} basal planes and {01\bar12} side planes. These results were obtained from the experimental condition of the incident electron beam being parallel to both basal planes and side planes of the sliced samples, which was confirmed by sharpness of the contrast of crystal edges at low magnification and also the homogeneous contrast of lattice images near the crystal edges at high magnification. Furthermore, it was disclosed that some of the particles contained stacking faults on {0001} planes and/or twins.