High-energy X-ray diffraction studies of i-Sc₁₂Zn₈₈

Abstract

Although quasicrystals form in a wide variety of ternary and quaternary metallic alloys, examples of stable binary icosahedral quasicrystals are quite rare. Indeed, it has been a decade since the discovery of icosahedral phases in Yb–Cd and Ca–Cd. We have discovered millimeter-sized facetted grains of i-Sc₁₂Zn₈₈ with icosahedral (pentagonal dodecahedral and rhombic triacontahedral) morphologies in solution-grown samples. Structural characterization of the bulk icosahedral phase was accomplished through single-grain high-energy X-ray diffraction. For both growth morphologies, all diffraction peaks could be indexed by a primitive (P-type) icosahedral phase. The two types of morphology do, however, present interesting differences in their respective degrees of quasicrystalline order.

Keywords:

• icosahedral
• quasicrystal
• solution growth
• high-energy diffraction

Acknowledgements

The authors wish to acknowledge the invaluable assistance of, and discussions with, C.-S. Ho, X. Lin, A. Kracher, K.W. Dennis, R.W. McCallum, T. Lograsso, M.J. Kramer and P. Thiel. Work at the Ames Laboratory was supported by the US Department of Energy, Basic Energy Sciences under Contract No. DE-AC02-07CH11358. The use of the Advanced Photon Source was supported by the US DOE under Contract No. DE-AC02-06CH11357.