THE STRUCTURE OF AL3PD - CLOSE RELATIONSHIP TO DECAGONAL QUASI-CRYSTALS

The crystal structure of the Al3Pd phase, considered to be a closely related structure to decagonal quasicrystals with a period of about 1.6 nm, has been determined by a combination of single-crystal X-ray analysis and high-resolution electron microscopy. The atomic model, which has about 280 atoms in an orthorhombic unit cell with parameters a = 2.336 nm, b = 1.232 nm and c = 1.659 nm and has the space group Pna2(1) (No. 33), was refined by a least-squares method with the Unics III system to a final R of 0.072 for 2348 unique reflections. The structure can be characterized as a two-dimensional arrangement of decagonal atom columns.