Short-Range Order and Long-Range Order of Fe Atoms in a Spin-Glass Phase and a Cluster-Glass Phase of Intercalation Compounds Fe_xTiS₂

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X-ray structural studies using single crystals have been performed for various concentrations x of intercalation compounds Fe_xTiS₂. Atomic arrangements of Fe atoms were found to be of short-range order in the spin-glass region and long-range order in the cluster-glass region. In x=0.15 (spin-glass), nearly spherical diffuse scattering was observed, whose maxima were at (1/2, , 0, , 1/2), (0, , 1/2, , 1/2), (1/2, , 1/2, , 1/2) and their equivalent positions. By means of an anomalous X-ray scattering technique, it was found that the short-range order of Fe atoms has a hexagonal symmetry. In x=1/4 (cluster-glass), 2√ 3a× 2a× 2c superlattice reflection was observed, and the crystal symmetry changed to monoclinic with the space group C2/m. In x=1/3 (cluster-glass), √ 3a× √ 3a× 2c superlattice reflection was observed, and the space group was P31c.