Apparent icosahedral symmetry is due to directed multiple twinning of cubic crystals
Abstract
A proposed structure and successful analysis of a diffraction pattern are offered to settle the question of the nature of the 'icosahedral' MAl6 alloys (where M = Cr, Mn, Fe). How a molten alloy of Mn (or Cr or Fe) and Al might react to sudden cooling is predicted. It is discovered that such an alloy on sudden cooling could form a mestastable cubic crystal with a large cube edge, about 26.7 A, with the unit cube containing about 1120 atoms (possibly a few more), and that these crystals would show ordered multiple growth such that 20 of them, roughly tetrahedral in shape, grow out from a central seed in such a way as to produce an aggregate with approximately icosahedral symmetry.
- Publication:
-
Nature
- Pub Date:
- October 1985
- DOI:
- 10.1038/317512a0
- Bibcode:
- 1985Natur.317..512P
- Keywords:
-
- Crystal Structure;
- Cubic Lattices;
- Symmetry;
- Twinning;
- Aluminum Alloys;
- Electron Diffraction;
- Manganese Alloys;
- Solid-State Physics