Quasicrystal approximant Ho₁₃Zn₅₈: an incommensurate modulated tunnel structure

S.Y. Piao (1) , S Lidin (2)

1 Inorganic Chemistry
2 Stockholm University

In a systematic study of the binary quasicrystal approximants RE₁₃Zn_∼58 (RE=rare earth elements) system, single crystals of Ho₁₃Zn₅₈ have been prepared. It is unique among the family members of the RE₁₃Zn_∼58 system, in that it shows a modulated superstructure ordering. Satellite reflections observed in single crystal X-ray diffraction pattern indicate the presence of a one-dimensional lattice distortion. The modulated structure has been solved and refined from X-ray data using the superspace group approach. The Ho₁₃Zn₅₈ structure can be described in the (3+1)-dimensional superspace group Pc2₁n (0β0)s0s with lattice parameters a=24.6481(7)Å, b=14.2484(4)Å, c= 14.0153(3)Å and a modulation vector q=(0, 0.741, 0). The crystal structure is closely related to those of the other RE₁₃Zn_∼58 compounds, comprising hexagon-shaped tunnels, made up of rare earth centred Zn polyhedra. All atoms in the structure are affected by a displacive modulation but one set of Zn atoms are very strongly affected, and display an almost composite behaviour with regard to the rest of the structure.

Mots clés: Physical Sciences

S.Y. Piao, S Lidin. Quasicrystal approximant Ho₁₃Zn₅₈: an incommensurate modulated tunnel structure. Philosophical Magazine, 2007, 87 (18-21), pp.2693-2699. ⟨10.1080/14786430601047715⟩. ⟨hal-00513798⟩