Formation of cadmium sulfide and zinc sulfide mixture in the interlayer space of montmorillonite

Cadmium sulfide and zinc sulfide (CdS and ZnS) were incorporated in sodium and cetyltrimethylammonium montmorillonites by the precipitation of sulfides from soluble metal sources in the presence of montmorillonites. The resulting shybrids were characterized by XRD, themogravimetric/differential thermal analysis (TG-DTA), TEM, Raman spectroscopy, and UV/Vis and photoluminescence spectroscopy. The absorption onsets owing to CdS and ZnS in cetyltrimethylammonium-montmorillonite appeared in a shorter wavelength region (311-520 nm) relative to that (309-484 nm) of the two semiconductors in sodium montmorillonite, thus reflecting the difference in the particle sizes of CdS and ZnS in the hybrids. The appearance of the broad emission bands combined with the bands centered at 469, 451, 440, and 431 nm owing to CdS and ZnS were attributed to the existence of both CdS and ZnS in the products. The difference in the emission intensity of the hybrids is discussed in terms of the role of the cetyltrimethylammonium cation. The unique optical properties of the two products were thought to occur through the interactions of sulfides with their environment (montmorillonite and cetyltrimethylammonium cation). A mixture of CdS and ZnS was prepared in unmodified and organically modified montmorillonite. The products showed emission bands owing to both CdS and ZnS. The blueshift of absorption onsets and the increase in PL intensity were caused by the confinement effect. CdS and ZnS formed separately in different interlayer spaces (segregation).