Structure of the Al65Rh27Si8 2/1–2/1–2/1 approximant

Atomic arrangements in the thermodynamically stable Al65Rh27Si8 2/1–2/1–2/1 approximant were determined by means of synchrotron radiation Rietveld analysis. It was found that the Al65Rh27Si8 2/1–2/1–2/1 approximant possesses a cubic unit cell containing 564 atoms. We found that the atomic structure of this approximant is characterized by a CsCl-type structure with a large icosahedral atomic cluster of 19.76 Å and a small icosahedral cluster of 6.8 Å in diameter. The presence of chemical and structure disordering between (Al, Si) and Rh was also found in the structure as well as in the Mackay-type 1/1–1/1–1/1 approximants.