Additional evidence from x-ray powder diffraction patterns that icosahedral quasi-crystals of intermetallic compounds are twinned cubic crystals.
Analysis of the measured values of Q for the weak peaks (small maxima, usually considered to be background fluctuations, "noise") on the x-ray powder diffraction curves for 17 rapidly quenched alloys leads directly to the conclusion that they are formed by an 820-atom or 1012-atom primitive cubic structure that by icosahedral twinning produces the so-called icosahedral quasi-crystals.
Linus Pauling Institute of Science and Medicine, 440 Page Mill Road, Palo Alto, CA 94306.
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