Single crystal neutron diffraction of decagonal Al72.5Co11Ni16.5

A single crystal of the thermodynamically stable decagonal phase in the system Al–Ni–Co with the nominal composition Al72.5Co11Ni16.5 was first studied by neutron diffraction. The diffraction experiment showed that the investigated crystal was a true single crystal. In a preliminary experiment we have measured a selection of Bragg reflections, diffuse scattering and satellite scattering and compared the observations with corresponding X-ray results. From this comparison we may conclude, that the 10mm symmetry is not due to the indiscernibility of Co and Ni atoms (X-rays), but a true structure feature. The superorder satellite scattering is basically not due to a Co/Ni ordering problem.