Influence of chelation ratio of metal alkoxides on aging of PZT 53/47 sol-gel-based precursors

The high reactivity of metal alkoxides, common starting reagents in sol-gel-based synthesis routes, generally demands the use of chelating agents in order to avoid fast hydrolysis and also to allow an easier manipulation of intermediates as well as final solutions. Under these conditions, stability issues sometimes can be linked to chelation issues that, therefore, should deserve a proper study suited to the material system of interest and, more specially, when considering the use of sol-gel-based precursors in research, small-scale applications and industry. In this work, we explore the sol-gel-based synthesis route of lead zirconate titanate (Pb(Zr0.53Ti0.47)O3 or PZT 53/47) using acetylacetone-chelated propoxides as intermediate reactants. Our main purpose here is to analyse the influence of the alkoxides:acetylacetone chelation ratio on the time evolution of mean particle size in the resultant organic colloidal dispersion used as PZT precursor. Purposely, we explored three different scenarios for chelation: (i) defective chelation, (ii) optimal chelation and (iii) excessive chelation. The time dependence of mean particle size was recorded by dynamic light scattering (DLS) measurements and aggregation kinetics was then explored by considering a diffusion-limited colloidal aggregations (DLCA) model.