Evidence from electron micrographs that icosahedral quasicrystals are icosahedral twins of cubic crystals.
An analysis of electron micrographs of Al5Mn quasicrystals obtained by rapidly cooling a molten alloy with composition Al17Mn and removing the Al matrix by electrosolution, revealing aggregates of 20 microcrystals at the corners of a pentagonal dodecahedron, supports the proposal that these microcrystals are cubic crystals twinned about an icosahedral seed, with each cubic microcrystal sharing a threefold axis and three symmetry planes with the seed.
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Linus Pauling Institute of Science and Medicine, Palo Alto, CA 94306, USA.