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-ra y diffractometry and Rietveld refinement for 2,4, 5 and 6 at. % Cu. Th e increase in the copper content is realized by the permanent replacem ent of the Al atoms by Cu in the (x0z) plane of the binary Al13Co4 str ucture. For up to 2 at.% of Cu this occurs at the (0.5, 0, 0.5) positi on. 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.