Effects of additives in electrospraying for materials preparation

TiO2 thin films and ZrO2 fine powders were prepared by electrostatic spray deposition (ESD). The morphology of the thin films and the particle size of the powders can be varied considerably by adding well-chosen additives to the precursor solutions. Acetic acid (HOAc) and ammonia nitrate (NH4NO3) were used as a solution chemistry modifier and a conductivity enhancement additive, respectively. It is found that by adding HOAc in an alcoholic precursor solution of Ti(OPri)(4), the structure of the deposited TiO2 films changes from severely cracked to crack-free reticular. In the ZrO2 powder preparation, the particle size of ZrO2 decreases substantially, i.e. from 3.5 mu m down to I mu m upon adding NH4NO3 in the precursor solution of zirconium acetylacetonate. Quantitative analysis of the impedance spectroscopy data of their precursor solutions has supported this result. (C) 1998 Elsevier Science Limited. All rights reserved.