抄録
In vacuum co-deposited film of manganese and aluminium, a disordered layer structure is found in the intermediate stage of heating, at a temperature between 500 and 600°C, when the film has a composition in the range between 25 and 35 at. per cent of manganese. Its reciprocal lattice is investigated by electron diffraction. The structure is interpreted on the basis of δ(Mn–Al) structure. For the combined atomic layer ot 8.5 Å thickness parallel to (010) plane, another stacking position denoted by C than the usual one denoted by B in the δ(Mn–Al) structure is found to be possible. This position gives a new stacking order of AC which may be considered as an antipode of the δ(Mn–Al) structure, the usual δ(Mn–Al) structure being denoted by AB-structure. Here the lateral displacements of B- and C-layers relative to A-layer are approximately given by am⁄2 and cm⁄2 respectively, where am and cm are two translational vector parallel to the layer. The observed extinction rule for the diffraction spots and their complicated arrangement are well explained by considering the coexistence of both AB- and AC-structures in the film.
