Introduction. The synthesis of binary metal chalcogenides of group II semiconductors has received much attention recently due to their important nonlinear optical properties, 1 luminescent properties, 2 quantum size effects, 3,4 and other important physical and chemical properties. [5][6][7] Considerable progress has been made in the synthesis of group II-VI semiconductor crystallites or nanocrystallines. 1,6,[8][9][10][11][12][13][14][15] However, these methods involved using either complex organometallic precursors 1,6,[8][9][10][11][12] or toxic gas H 2 E. 13 Since these II-VI materials form defects and interdiffuse at temperature above ca. 500 °C, the low-temperature growth of the II-VI crystalline materials is a major consideration. 11 Parkin et al. 14

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Nanocrystalline CdS with different morphologies and particle sizes was obtained via a novel solvothermal reaction between cadmium salts such as Cd(NO 32 O and thiourea (Tu) at relatively low temperature. It is found that solvents play an important role in controlling the morphology and particle sizes of the nanocrystalline CdS product. The effect of solvents, anions of the cadmium salt, the molar ratio of Tu to the cadmium salt, and temperature on the morphology, particle sizes and phase of nanocrystalline CdS products has been investigated.

A novel one-step solvothermal decomposition process (SDP) was successfully developed for fabrication of Bi 2 S 3 nanowires via a reaction between BiCl 3 and thiourea in polar solvents at 140°C for 6-12 h. The influence of solvents, reaction temperature, and reaction time on the formation of Bi 2 S 3 nanowires was investigated. The yield was as high as 98%. The particle sizes of Bi 2 S 3 nanowires are controlled by the choice of solvents. The possible formation mechanism of Bi 2 S 3 nanowires via the so-called SDP method is proposed. The present technique is expected to synthesize other nanostructural metal chalcogenides under mild conditions.

A novel synthesis method was introduced for the nanocomposites of cadmium sulfide and montmorillonite. This method features the combination of an ion exchange process and an in situ hydrothermal decomposition process of a complex precursor, which is simple in contrast to the conventional synthesis methods that comprise two separate steps for similar nanocomposite materials. Cadmium sulfide species in the composites exist in the forms of pillars and nanoparticles, the crystallized sulfide particles are in the hexagonal phase, and the sizes change when the amount of the complex for the synthesis is varied. Structural features of the nanocomposites are similar to those of the clay host but changed because of the introduction of the sulfide into the clay.