a1 Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge, MA 02139, USA
The defect structures of Fe9S10 have been studied by high-resolution transmission electron microscopy. Lattice images of the 3C and 4C superstructures and at least one other phase, which has not been previously reported, were observed. It has been found that the 4C superstructure transforms into the 3C superstructure rather than the MC phase as previously suggested. Intrinsic stacking faults in the sulfur sublattice and two different types of vacancy-ordering antiphase domains were also observed. Evidence from optical diffratograms of areas containing these defects suggests that complex features in the electron diffraction pattern may be artifactual.