抄録
Au3Cd which is an ordered alloy with the one-dimensional regular anti-phase domain structure exhibits an asymmetry in intensity of components of each pair of split superlattice reflections in X-ray single crystal diffraction patterns, the splitting being caused by the presence of the periodic anti-phase domains. The nature of lattice modulation revealed by this intensity asymmetry has been investigated in detail. Fourier synthesis has been made using (h0l) type reflections and the crystal structure has been refined taking into account the information obtained from the synthesis. The result shows that the modulation is nothing but the periodic displacements of atoms from the normal positions, gold atoms being displaced away from the anti-phase domain boundaries by 0.015±0.005 Å and cadmium ones being displaced in the opposite directions by 0.028±0.005 Å. This type of lattice modulation seems not to contradict the idea suggested by Sato and Toth that the ordered alloys with long period are stabilized by the contact of Fermi surface with Brillouin zone boundaries.
