Distance distributions about MN in Icosahedral and Crystalline AL-MN-SI.

We report EXAFS measurements on icosahedral and orthorhombic Al(6)Mn, icosahedral Al(74)Mn(20)Si(6), and a-Al(100)Mn(24)Si (14). We find close resemblance between a-phase and i-Al (74)Mn(20)Si(6), and poorer agreement between a-phase and i- Al(6)Mn. Neither icosahedral phase showed much resemblance to the orthorhombic phase. We conclude that the icosahedral Al(74)Mn(20)Si(6) resembles a distorted a-phase and so may be built of icosahedra, glued together with Al as in the a structure. Icosahedral Al(6)Mn is perhaps a more disordered version of the above.