Synthesis of monodisperse CdS and ZnS particles from concentrated solutions of the EDTA-metal complexes

Monodisperse CdS particles with mean diameter 0.51 μm having 3.33% coefficient of variation (relative standard deviation) in size distribution were obtained in large quantities by instantaneous addition of 5 ml of 1.2 mol dm ^-3 thioacetamide (TAA) containing 1 wt% gelatin to 20 ml of Cd-EDTA solution consisting of 0.300 mol dm ^-3 Cd(OH) ₂ , 0.303 mol dm ^-3 EDTA · 2Na, 2.0 mol dm ^-3 CH ₃ COONH ₄ , 0.6 mol dm ^-3 NH ₃ , and 1 wt% gelatin. After the addition of the TAA solution, the system was aged for 8 h at 60°C under agitation. The yield was 91.5%. Uniform ZnS particles of mean diameter 0.73 μm with a 4.08% coefficient of variation in size distribution were also obtained by analogous preparation procedures in which Zn(NO ₃ ) ₂ was used in place of Cd(OH) ₂ .