High-voltage, high-resolution electron microscopy of Au-Cd alloys. III. One-dimensional long-period superstructure of DO₂₃ type

A one-dimensional long-period superstructure (1d - LPS) of Au-24 at.% Cd alloy has been investigated at the atomic level with a 1 MV electron microscope. Simple images interpretable in terms of the 1d - LPS of DO₂₃ type are observed; the cadmium atom positions appear as a regular out-of-step configuration of bright dots with the spacing of the lattice constant (4.1 Å) of the basic f.c.c. cell. This is called a superstructure image. The formation of the superstructure image is studied as functions of specimen thickness and defocus on the basis of n-beam multislice calculations.