In situ study of single aqueous droplet solidification of ceramic precursors used for spray pyrolysis

The electrodynamic balance (EDB) is demonstrated to be useful for the in situ study of aqueous droplet solidification. We have used an EDB to study the solidification of solution droplets used for ceramic powder synthesis by spray pyrolysis. The mass change and the elastic light scattering of the drying 20 μm solution droplets were monitored. We found that aqueous MgCl₂ droplets crystallize but Mg-(COOCH₃)₂, MgSO₄, ZrO(OH)Cl, and Zr(COOCH₃)₄ droplets appear to form gels at high concentrations. As a result of the gel formation, the rate of loss of water from the droplets can be reduced by approximately 150 times and drying is limited by solute diffusion in the gel.