Structure of PbMnO2.75 determined by electron crystallography

The PbMnO_{3– x} system has a great number of phases with large unit cells for different values of x. In the present work, we study a PbMnO_2.75 phase that has proven too complex to be solved by X-ray powder diffraction. Using electron crystallography, we have determined the positions of all metal atoms without the necessity of using a model as a starting point. The results correspond, within experimental uncertainties, to those obtained by Bougerol et al. (J. Solid State Chem. 169 131 (2002)).