THE STRUCTURE OF THE (AL, CU)13CO4 PHASE WITH DIFFERENT CU CONTENT

The structure of the (Al, Cu)13CO4 phase was determined by powder X-ray diffractometry and Rietveld refinement for 2,4, 5 and 6 at. % Cu. The increase in the copper content is realized by the permanent replacement of the Al atoms by Cu in the (x0z) plane of the binary Al13Co4 structure. For up to 2 at.% of Cu this occurs at the (0.5, 0, 0.5) position. For the higher Cu content its atoms occupy completely or partially two other positions, whose coordinates for the 6 at.% Cu phase are (0.890, 0, 0.200) and (0.075, 0, 0.777). No partial occupancies of pure Al-sites are suggested for the 2-6 at.% Cu.