A shift-lattice description of some face centred cubic alloy superstructures

Abstract

The structures of the experimentally prepared binary alloys Au₃₁Mn₉ (two forms), Au₇₂Mn₂₁ , Au₉₅Mn₂₈ , Au₂₇Mn₈ , Au₁₆₇Mn₄₉ and Au₃Mn (one form), have been analysed and found to be two-dimensional shift-lattices. It is shown that both the Au and Mn atom arrays lie upon separate but complementary shift-lattices. The known structures form only a small part of an infinite family of commensurate and incommensurate structures which can be constructed by smoothly varying the shift-lattice parameters applicable to the known phases. The two-dimensional shift-lattice structures described here are shown to be constructed from fragments of simpler one-dimensional shift-lattices analysed previously.