Growth and physical properties of the decagonal Al–Cu–Co quasicrystal grown from the ternary melt

Abstract

Large faceted single-grain quasicrystals of the approximate composition Al_63.2Cu_19.5Co_17.3 and with a high degree of structural perfection are obtained through the slow cooling of a ternary melt with initial composition Al₆₅Cu₂₉Co₆. X-ray diffraction patterns of crushed single-grain samples are exceptionally sharp, indicating a high degree of structural order, with no evidence of secondary phases. Transmission electron micrographs also reveal sharp diffraction patterns in the even-n layers but diffuse scattering in the odd-n layers. Temperature-dependent magnetization, electrical resistivity and specific heat are measured using bars cut perpendicular and parallel to the c axis and show diamagnetic behaviour: γ ≈ 0.5 mJ mol⁻¹ K⁻², ρ _c(2 K) ≈ 52 μΩ cm and ρ _q(2 K) ≈ 283 μΩ cm.

Acknowledgements

The authors would like to thank J.D. Strand for useful comments, H. B. Rhee for help in sample preparation and Salomé O. Wilde for help in cutting. Ames Laboratory is operated for the US Department of Energy by Iowa State University under contract W-7405-Eng.-82. This work was supported by the director for Energy Research, Office of Basic Energy Sciences.