Quasicrystals and their approximants

Sven Hovmöller and Xiaodong Zou

The Nobel Prize in chemistry 2011 was award to Daniel Shechtman for his discovery of quasicrystals; an AlMn alloy having 5-fold symmetry.

Quasicrystals (QC) containing the "forbidden" 5-, 8-, 10- and 12-fold symmetries present a great challenge to the structural chemist. Different approaches may be used to solve such structures. We have used X-ray crystallography, electron microscopy and electron diffraction data combined with crystallographic image processing for solving approximants to 10- and 12-fold QC. We have also constructed a model for an 8-fold quasi-crystal.
Approximants are chemically and structurally closely related to quasicrystals. They are very complicated but have true classical crystal structures.
    This work started as a collaboration with Prof. Kehsin Kuo’s group in the Beijing Laboratory of Electron Microscopy (BLEM), Chinese Academy of Sciences.

    References:

2011 Hovmöller,S., Zou,X.D., Hovmöller Zou,L., Grushko,B., Structures of pseudo decagonal approximants in Al-Co-Ni. Phil Trans Roy Soc A (2011) in press.

2010 Li,M.R., Sun,J.L., Hovmöller,S., Zou,X.D., Oleynikov, P. and Grushko,B. A complicated quasicrystal approximant epsilon16 solved by the strong reflections approach. Acta Cryst. B66 (2010) 17-26.

2008 Li,M.R., Hovmöller,S., Sun,J.L. and Kuo,K.H. Crystal structure of the 2/1 cubic approximant Ag42In42Yb16. Journal of Alloys and Compounds 465 (2008) 132-138.

Zhang,H., Wang,S.J., Wang,S.C., Li,Z.C., Hovmöller,S. and Zou,X.D. “A Structure Model for tau2-Al13Co4 deduced by the strong reflections approach” J. Computational and Theoretical Nanoscience, 5 (2008) 1735-1737.

2006 Zhang,H., He,Z.B.,Oleynikov,P., Zou,X.D.,Hovmöller,S. and Kuo,K.H. Structure model for the tau(mu) phase in Al-Cr-Si alloys deduced from the lambda phase by the strong-reflections approach. Acta Cryst. B62 (2006) 16-25.

Oleynikov,P., Demchenko,L., Christensen,J.,Hovmöller,S., Yokosawa,T., Döblinger,M., Gruschko,B. and Zou,X.D., Structures of the pseudodecagonal Al-Co-Ni approximant PD4. Philosophical Magazine 86 (2006) 457-462.

2005 Zhang,H., Zou,X.D., Oleynikov,P. and Hovmöller,S. Structures relations in real and reciprocal space of hexagonal phases related to i-ZnMgRE quasicrystals. Philosophical Magazine 86 (2005) 543-548.

2004 Christensen,J., Oleynikov,P., Hovmöller,S. and Zou,X.D. Solving Approximant Structures Using a "Strong Reflection" Approach. Ferroelectrics 305 (2004) 273-277.

2003 Zou,X.D, Mo,Z.M., Hovmöller,S., Li, X.Z. and Kuo,K. Three dimensional reconstruction of the v-AlCrFe phase by electron crystallography. Acta Cryst.A59 (2003) 526-539.

2001 Boström,M and Hovmöller,S. Preparation and Crystal Structure of the Novel Decagonal Approximant Mn₁₂₇Ga₁₃₃ J. Alloys and Compounds. 314 (2001) 154-159.

Boström,M and Hovmöller,S.A pentagonal cluster in certain approximants to decagonal quasicrystals Acta Cryst B57 (2001) 646-651.

2000 Boström,M. and Hovmöller,S. Preparation and Crystal Structure of the Pseudo Decagonal Approximant Ga₅Mn₃ J. Solid State Chem. 153 (2000) 398-403.

1997 Sui,H.X., Liao,X.Z., Kuo,K.H. Zou,X.D. and Hovmöller,S. Structural model of the non-Fibonacci approximant in the Al₁₂Fe₂Cr alloy. Acta Cryst. B53 (1997) 587-595.

1995 Jiang,J.C., Hovmöller,S. and Zou,X.D. A three-dimensional structure model of eight-fold quasicrystals obtained by high-resolution electron microscopy Phil.Mag.Lett. 71 (1995) 123-129.

1988 Wang,D.N., Ishimasa,T., Nissen,H.U., Hovmöller ,S. and Rhyner,J. Dislocations, Domains and Quenched Phonon and Phason Strains in Al-Mn Quasicrystals Observed by Electon Microcsopy. Philosophical Magazine (1988) 58, 737-752.