KIKUCHI PATTERNS, INDEX SYSTEM AND INFLATION PROPERTIES OF AN AL70CO15NI15 DECAGONAL QUASI-CRYSTAL

The general principle of the projection method and an index scheme for decagonal phases are described systematically. Kikuchi-line patterns over a large angular range from an Al70Co15Ni15 decagonal quasicrystal with a periodicity of 4 angstrom along the tenfold axis were obtained by connecting a series of large-angle convergent-beam electron diffra ction patterns. Computer-simulated electron diffraction patterns of ma jor zone axes and Kikuchi-line patterns covering the whole orientation triangle show good agreement with the patterns recorded experimentall y. After discussion of the inflation and deflation properties, appropr iate quasilattice parameters of a = 6.6 angstrom (or 2.5 angstrom), c = 4.0 angstrom for an Al70Co15Ni15 decagonal quasicrystal are chosen t hat are suitable for atomic decoration of the quasilattice of the deca gonal phase.