Abstract
With standard x-ray diffraction it is often impossible to solve structures in multi-phase materials. Electron probes offer diffraction from micron-sized areas though dynamical effects will be present. Here we describe a structural analysis using electron diffraction from a metastable phase in the Al-Ge system. Preliminary analysis had provided a trial structure, that is summmarised here. This phase, found in recrystallised, amorphous equiatomic Al-Ge films, was body centred tetragonal with space group I/4mcm and a=6.26Å; c=5.0Å, which was consistent with the C16 structure. To confirm the structure a set of medium order intensities was obtained from LACBED zone axis patterns around [001]. On a zone axis we find annuli filled with a network of non-systematic HOLZ reflections from a single layer in the reciprocal lattice. Thus for thin, strain-free crystals, their intensities can approach the kinematic limit. Conditional Patterson transforms of the intensities for both hkl and hk2 reflections gave peaks corresponding to inter-string vectors in agreement with the C16 structure.
Published Version
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