THE STRUCTURE OF AN AL3MN-TYPE AL-3(MN, PD) CRYSTAL STUDIED BY SINGLE-CRYSTAL X-RAY-DIFFRACTION ANALYSIS

The structure of a single-crystal with a composition of approximately Al75Mn20Pd5, which is isostructural to the Al3Mn phase, has been inves tigated by X-ray diffraction analysis. The refinement of the structure was carried out with data from 2197 observed reflections (intensity I > 2.0 sigma(I)) by the least-squares method to a final R value of 0.0 62. Pd atoms partially replace Al atoms at definite positions in the A l3Mn structure and show a mixed occupancy with Al atoms, with their po sitions significantly shifted along the b-axis. On the basis of the st ructure of the Al-3(Mn, Pd) phase, we discuss the positions of Pd atom s in the Al-Pd-Mn decagonal quasicrystal.