Formation of colloidal dispersions from supersaturated iron(III) nitrate solutions v. Synthesis of monodisperse goethite sols

Effect of the range of repulsions on the existence of a stable liquid phase

Experimental and theoretical results have established that the range of the attraction plays a critical role in determining whether a particle system exhibits a stable liquid phase. Changes to the range of the repulsions can similarly affect the existence of a stable liquid phase; however, these effects have not been clearly elucidated. We demonstrate that an increase in the range of repulsions can either enhance or decrease the stability of the liquid phase, depending on the form of the interaction potential. For either case, the critical variable that controls the stability of the liquid phase is the ratio of the representative energies of the liquid and solid phases.

Precipitation of Uniform Particles: The Role of Aggregation

The conventional mechanism developed by LaMer (1) is often considered as the most relevant model for describing the precipitation of uniform particles. In this model, the concentration of a species is slowly increased above its equilibrium value until a critical concentration is reached and nucleation occurs. The resulting particles consume soluble species and the supersaturation level is reduced until there is a balance between particle growth and the generation of reactive species. At this point nucleation stops. Particle growth then continues by molecular addition of soluble species to the growing particles. Uniformity is achieved through a short nucleation time and a particle growth mechanism where the small particles grow more rapidly than the large particles.