The new technique of electron holography is reviewed. Using this technique, the phase distribution of an electron beam transmitted through a specimen is observed in the interference electron micrograph. The contour lines that appear can be interpreted as the thickness contours of a homogeneous specimen and as the magnetic lines of force of a ferromagnetic specimen. Several applications and future prospects are presented using this holographic interference method. [J. Cryst. Soc. Jpn. 26, 211 (1984) ] .
The distribution of cations in TixV1-xS1.40 (0≤x≤1), TixV1-xS1.57 (0≤x≤1) and FexV3-xS4 (0≤x≤2), which have metal-deficient NiAs-like structures, is investigated by magnetic susceptibility, NMR and Mössbauer experiments. It is made clear that these cations increase the preferential occupation of the sites in the metal-full layers of each structure in the order of Ti, V and Fe which coincides with that of the ionization tendency. The interaction between metal atoms neighbouring along the c axis plays an important role in the site preference and magnetic properties. [J. Cryst. Soc. Jpn. 26, 220 (1984) ] .
The X-ray standing wave method, which has been applied to the determination of the atomic structure of the crystal surface and interface, is reviewed. Firstly some topics on the determination of the position of surface adsorbates by this method are summarized. Secondly the studies on the determination of the atomic structure of the interface between an epitaxial film and a substrate crystal, which have been investigated by the present authors, are reported. [J. Cryst. Soc. Jpn. 26, 228 (1984) ] .