Rare-Earth Oxysulfoarsenates.-Phase equilibria studies in the Ln2O2S-As2S3 system (Ln: Eu, Er, Yb) result in the detection of the compounds LnAsOS2 and (LnO)4As2S5. X-ray studies indicate that the last mentioned compounds crystallize in the tetragonal system (space group I4/mmm). The oxosulfoarsenates LnAsOS2 belong to the structure type CeBiOS2 and crystallize in the tetragonal system P4/mmm with Z=2. -(TANRYVERDIEV, V. S.; ALIEV, O. M.; ALIEV, I. I.; Neorg. Mater. 33 (1997) 7, 860-863; Inst. neorg. fiz. khim. Akad. nauk Azerb. Resp., Baku, Azerbaijan; RU)

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Synthesis and Physico-Chemical Properties of LnBiOS2.-Compounds of the composition LnBiOS2 (Ln: La, Ce, Pr, Nd, Sm, Gd, Dy, Yb) are synthesized by annealing Bi2S3 and Ln2O2S2 and subjected to single crystal growth according to the method of chemical transport reaction. Single crystal X-ray studies indicate that the LnBiOS2 compounds are isostructural to known CeBiOS2 and crystallize in the tetragonal system (space group P4/nmm, Z = 2). All the prepared sulfides turn out to be semiconductors. -(TANRYVERDIEV, V. S.; ALIEV, O. M.; ALIEV, I. I.; Neorg. Mater.

Synthesis and Properties of CdLn 2 X 4 (X: S, Se, Te) and CdLn 4 S 7 Chalcogenides.-The formation of the ternary compounds CdLn 2 X 4 (I) and CdLn 4 X 7 (II) in the CdX-Ln 2 X 3 systems is established. Single crystal XRD studies indicate that compounds (I) of the cerium subgroup crystallize in the cubic system (Th 3 P 4 -type), compounds (I) of the yttrium subgroup have a spinel-type structure, and that compounds (II) are isostructural to Y 5 S 7 . The compounds CdLn 2 S 4 (Ln: La, Ce, Pr, Nd, Sm, Gd, Tb) prove to be p-type semiconductors. -(ALIEV, O. M.; AGAEV, A. B.; AZADALIEV, R. A.; Neorg.