Kikuchi patterns, index system and inflation properties of an Al70Co15Ni15 decagonal quasicrystal

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 A along the tenfold axis were obtained by connecting a series of large-angle convergent-beam electron diffraction patterns. Computer-simulated electron diffraction patterns of major zone axes and Kikuchi-line patterns covering the whole orientation triangle show good agreement with the patterns recorded experimentally. After discussion of the inflation and deflation properties, appropriate quasilattice parameters of a=6.6 A (or 2.5 A), c=4.0 A for an Al70Co15Ni15 decagonal quasicrystal are chosen that are suitable for atomic decoration of the quasilattice of the decagonal phase. (orig.)