Crystal structure of the Al 8 Cr 5 -type inter-metallic Al 7.85 Cr 5.16 .

An aluminium-deficient Al 8 Cr 5 -type inter-metallic with formula Al 7.85 Cr 5.16 (octa-aluminium penta-chromium) was uncovered when high-pressure sinter-ing of a mixture with composition Al 11 Cr 4 was carried out. Structure analysis reveals that there are three co-occupied positions with refined occupancy factors for Al atoms being 0.958, 0.772 and 1/2. The present phase is confirmed to be isotypic with the previously reported rhombohedral Al 8 Cr 5 ordered phase [Bradley & Lu (1937). Z. Kristallogr. 96 , 20-37] and structurally closely related to the disordered phases of rhombohedral Al 16 Cr 9.5 and cubic Al 8 Cr 5 .