Synthesis of Single Crystals of Ternary Chalcohalides

Abstract

The chalcohalides of antimony and bismuth had already been synthesized before the end of the last century [1, 2]. However, only after the structure of these compounds had been studied by x-ray diffraction did the study of their optical, dielectric, and photoelectric properties really begin [3–6]. Of all the chalcogenides of antimony and bismuth, that which has atracted the greatest attention from research workers has been antimony sulfoiodide, which possesses both ferroelectric and photosemiconducting properties. Methods of producing chalcogenides as well as the external appearance of the compounds so formed, their physical and chemical properties, are described in [7]. Chalcohalides may be obtained (1) by the limited action of dry hydrogen sulfide on a heated (but not melted) halide (2) by melting the corresponding sulfides and halides together, and (3) by the interaction of sulfides with halides. It should be noted that the composition of the reacting mixtures is usually chosen empirically, without any real physicochemical basis for the conditions of synthesis. In order to establish a reasonable basis for this, it is essential to study the phase diagrams of the chalcogenide—halide systems M₂S₃—X₃, where M = Sb or Bi, X = Cl, Br, or I, as well as the chalogenide-chalcogen X₃—S(Se), the metal—chalcogen—halogen, and the chalcogenide-halogen systems.