THE SYNTHESIS OF QUANTUM-SIZE LEAD SULFIDE PARTICLES IN SURFACTANT-BASED COMPLEX FLUID MEDIA

The relative roles of the ion interactions, molecular complex formation, and the local structure of the medium on the formation of nano-sized particles of lead sulfide (PbS) in a nonionic surfactant/water/oil microemulsion have been investigated. Comparison of the reaction carried out under conditions of minimal hydrolysis of the cation (low pH) in two different counterion/acid systems (nitric or perchlorate) indicates that hydrolysis does not play a significant role in the production of PbS in fine particle form. Furthermore, the nature of the counterion, NO3 or ClO,4, used did not affect the particle formation. Variation in the composition of the microemulsion used (dodecyl tetracthoxyethylene glycol ether/water/hexane) showed little effect on the particle formation. This finding implies that the presence of closed microemulsion droplets is not, per se, important for the precipitation of nano-sized particles in this case. Order of mixing studies implies that interaction of a complexation type is the most important step in the synthesis. © 1993 by Academic Press, Inc.