PREPARATION AND CHARACTERIZATION OF CDS AND ZNS PARTICLES IN NANOPHASE REACTORS PROVIDED BY BINARY LIQUIDS ADSORBED AT COLLOIDAL SILICA PARTICLES

Determinations of adsorption excess isotherms of silica particle dispe rsions in ethanol - cyclohexane and in methanol-cyclohexane binary mix tures have established the formation of 0.5-5.0 nm thick alcohol rich adsorption layers at the silica particle interface. The adsorption lay ers on silica particles, formed in methanol-cyclohexane = 0.01:99.99 ( mol/mol) and ethanol-cyclohexane = 0.05:99.95 (mol/mol), were used as nanophase reactors for the in situ generation of size-quantized CdS an d ZnS particles. The semiconductor particles were generated by the add ition of H2S to silica particle dispersions which contained different concentrations of Cd2+ or Zn2+. The smallest semiconductor particles w ere generated in dispersions which contained the least amount of precu rsors. Absorption spectrophotometry, small-angle X-ray scattering, rhe ological, and calorimetric measurements were used to characterize the dispersions. The presence of semiconductor particles increased the vis cosities and decreased the immersion wetting enthalpies of the silica dispersions, indicating strong interparticle interactions.