Spontaneous nucleation of monodisperse silver halide particles from homogeneous gelatin solution II: silver bromide

The spontaneous nucleation process of monodispersed AgBr particles by gradual release of silver ions from a Ag+–gelatin complex was studied on the basis of the fundamental theory and analytical procedures for a AgCl system in the preceding report in this volume. The nucleation mechanism is basically the same as the AgCl system, in which the nucleation of the stable nuclei is governed by the growth of the generated stable nuclei and the final particle number n∞ is determined by the equation, n∞=QoVm/υ̇, where Qo is the rate of increasing concentration of solute, Vm is the molar volume of the solid, and υ̇ is the volumic growth rate of a stable nucleus during the nucleation period. However, the final particle size in diameter was much smaller by a factor of 1/6 and the nucleation time was about 30 times longer than those in the AgCl system. This is mainly due to the much smaller υ̇ in the AgBr system as a result of the lower solubility of AgBr.