The aqueous deposition of calcium oxalate onto colloidal oxides has been
studied as a model system for understanding heterogeneous nucleation
processes of importance in biomimetic synthesis of ceramic thin films.
Calcium oxalate nucleation has been monitored by measuring induction times
for nucleation using Constant Composition techniques and by measuring
nucleation densities on extended oxide surfaces using an atomic force
microscope. Results show that the dependence of calcium oxalate nucleation
on solution supersaturation fits the functional form predicted by classical
nucleation theories. Anionic surfaces appear to promote nucleation better
than cationic surfaces, lowering the effective energy barrier to
heterogeneous nucleation.