Structure of the Pseudodecagonal Al-Co-Ni Approximant PD4

Peter Oleynikov (1) , Lesya Demchenko (1) , Jeppe Christensen (1) , Sven Hovmöller (1) , Tadahiro Yokosawa (1) , Markus Döblinger (2) , Benjamin Grushko (3) , Xiaodong Zou (1)

1 Structural Chemistry [Stockholm]
2 Ludwig-Maximilians-Universität München
3 Forschungszentrum

A model for the pseudodecagonal approximant PD4 in the Al-Co-Ni system was deduced from single crystal X-ray diffraction data. The space group is Bbmm with a = 101.3 Å, b = 32.1 Å, c = 4.1 Å. Atomic positions of 133 unique atoms in the unit cell with a reasonable geometry were found by Direct Methods and the difference Fourier syntheses. The obtained structure model is in good agreement with high resolution electron microscopy images of PD4. Diffuse scattering observed along the a* direction in the hkl layers with l = 1/2, 3/2 etc. indicates substantial disorder (lamellar stacking faults). If this diffuse scattering is taken into account, c = 8.2 Å.

Mots clés: Physical Sciences

Peter Oleynikov, Lesya Demchenko, Jeppe Christensen, Sven Hovmöller, Tadahiro Yokosawa, et al.. Structure of the Pseudodecagonal Al-Co-Ni Approximant PD4. Philosophical Magazine, 2005, 86 (03-05), pp.457-462. ⟨10.1080/14786430500270343⟩. ⟨hal-00513592⟩