Anomalous-X-ray scattering associated with short-range order in an Al70Ni15Co15 decagonal quasicrystal

The diffuse scattering around Bragg reflections was observed in a single de cagonal quasicrystal of Al70Ni15Co15 using anomalous-X-ray scattering. The intensities of diffuse scattering vary with the three incident X-ray wavele ngths, near the Co K-edge and the Ni K-edge and between them. The contrast of diffuse scattering shows the existence of atomic short-range order (SRO) between Ni and Co. The distributions of diffuse scattering are anisotropic ally modulated and the diffuse shapes vary from one reciprocal lattice poin t to another. in quasicrystals, anisotropic diffuse shapes derive from phas on strain. It is concluded that both SRO and phason strains exist in Al70Ni 15Co15. in addition, as the first neighbor of Ni, Ni is preferred to Co sta tistically, since SRO intensities appear about zone-centers, i.e. there is local clustering of these species. (C) 2000 Elsevier Science B.V. All right s reserved.