Study on the Ordered Alloys of Gold-Manganese System by Electron Diffraction, I. Au3Mn

The ordered structure of Au 3 Mn alloy has been investigated by electron diffraction using oriented, evaporated films. The structure can be thought of as formed from the fundamental face-centred orthorhombic lattice, in which the atoms arrange themselves as in the ordered lattice of Cu 3 Au but the first kind of out-of-step periodically occurs along both the x and y directions. In some cases the periods are 1.2 a 1 and 2.2 a 2 respectively, where a 1 =4.08Å, a 2 =4.05Å, a 3 =4.03Å are the lattice constants of the fundamental lattice. Thus, a two-dimensional anti-phase domain structure of a new type takes place, which belongs to the space group P nnm - D 2 h 12 in the idealized case.