Photoluminescence and structural characteristics of CdS nanoclusters synthesized by hydrothermal microemulsion

Spherical and uniform CdS nanoclusters were synthesized by hydrothermal mic roemulsion. The reaction of Cd2+ ions with S2- ions generated from the deco mposition of thioacetamide proceeded in water microdroplets. The mean diame ter of the CdS nanoclusters can be varied from 20 to 80 nm by increasing th e reaction temperature from 30 to 120 degreesC. XRD results indicate that t he resulting CdS nanoclusters have a reduced and distorted hexagonal lattic e compared to bulk materials. Two intense luminescence bands, i.e., green a nd red, were observed to coexist in the CdS nanoclusters. Their peak positi ons and relative intensities were found to be sensitive to the size and str ucture of nanoclusters. These emissions are attributed to surface defects ( green emission) and the Cd-Cl composite vacancies (red emission). (C) 2001 American Institute of Physics.