Abstract: The spherical nano-particles of AgI were prepared from Ag complexes. Diameter of AgI could be controlled to within 20 to 100 nm. The prerequisite of covering of Y(OH)CO3,obtained by the hydrolysis of Y(NO3)3 in the presence of urea, on the pre-existing spherical AgI particles was that the surface of pre-existing particles must be charged negatively. The results were effected by some factors, such as concentration of Ag complexes, Y(NO3)3,urea and pre-existing particles, reaction time, aging temperature, as evidenced by X-ray diffraction, TEM of particle experiments. The hollow particles of Y(OH)CO3 (see Fig.5) were prepared by the coordination reaction which dissolved the pre-existing particles of AgI in Na2S2O3 concentrated solutions.

Key words: Pre-existing particles, Covering, Independent nucleations, Surface charge, Hollow-particles, Complexes