Langmuir 1992,8, 299-302
299
Early Stages of HgI2 Aggregation in Aqueous Solution Jovan M. Nedeljkovib, Rajna Herak, and Olga I. Mibib* Boris KidriE Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Yugoslavia Received March 8, 1991. In Final Form: J u n e 25, 1991 Mercuric iodide colloidal particles prepared in aqueous solution change crystal structures during the early stages of particle growth. The structures of microcrystallites were determined by transmission electron diffraction and X-ray diffraction analysis. At the first stage, low molecularweight clusters (diameter 500 A) has an orthorhombic structure (Figure 5b) while the red (diameter >lo00 A) has a tetragonal structure (Figure 5c). The diffractogram of the yellow powder shows the following lines of orthorhombic modification: 002, 111, 004, 112, 113, and 023. Identification was done on the basis of thelattice parameter given by Jeffrey and Vlasse.18 Besides
:
Conclusion We conclude from a series of electron diffraction and X-ray analyses together with absorption and emission spectra that the crystal structure of HgI2 colloidalparticles changes when the particles are gradually allowed to crystallize and develop a long-range order. Low weight molecular clusters (
