Precession electron diffraction of Mn2O3 and PbMnO2.75: solving structures where X-rays fail.

The structure solutions of the two phases Mn(2)O(3) and PbMnO(2.75) by precession electron diffraction (PED) are presented. In the powder samples used these structures could not be solved by X-ray diffraction because Mn(2)O(3) is a minority phase in an MnO(2) powder and the complex structure of PbMnO(2.75) leads to severe peak overlap in the powder diffraction pattern. The influence of different parameters on the structure solution is studied, i.e. the number of reflections measured, precession angle, resolution limit and Lorentz-type correction. It is shown that the number of reflections is the most important parameter for successful structure solution from PED data.