Accepted for publication in Phil. Mag. B
On the growth of decagonal Al-Ni-Co quasicrystals from the ternary
melt
I.R. Fisher+*, M.J. Kramer+†‡, Z. Islam+*, A.R. Ross+, A. Kracher‡,
T. Wiener+*, M.J. Sailer+*, A.I. Goldman+* and P.C. Canfield+*
+Ames Laboratory,
*Department
of Physics and Astronomy,
†Department
of Materials Science and Engineering
‡Department
of Geological and Atmospheric Sciences,
Iowa State University, Ames, IA 50011.
High-quality, single-grain samples of decagonal
Al-Ni-Co quasicrystals with volumes of up to 0.8 cm3 and an approximate composition of Al72Ni11Co17 have been grown from the ternary melt. The precise growth methods and conditions
are discussed in detail. X-ray diffraction patterns of crushed single grains and of
single-grain samples are exceptionally sharp, indicating a high degree of structural
order, with no evidence of second phases. Transmission electron micrographs also reveal
sharp diffraction patterns in the even n layers but diffuse scattering in the odd n
layers, indicative of a structure intermediate between the Al73Co27 and Al69Ni31 end-members. The electrical
resistivity measured directly from cut bars for currents flowing perpendicular to the
crystalline direction (i.e. perpendicular to the c-axis) is non-metallic, with a broad
maximum around 180 K, and a value of approximately 310 mWcm at
300 K. The resistivity for currents flowing parallel to the c-axis is metallic, and is
almost an order of magnitude smaller in value than for i ^ c.
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