ELECTROSTATIC SOL–SPRAY DEPOSITION OF NANOSTRUCTURED CERAMIC THIN FILMS

Electrospraying has been developed into an electrostatic spray deposition technique for the deposition of ceramic thin films. The cone-jet spraying mode appears to be the most preferable for this purpose, and the domain where the cone-jet mode exists was found to depend strongly on the nozzle design. A nozzle with a large diameter and a tilted outlet widens the windows for both the applied high DC voltage and the flow rates of a precursor liquid keeping the cone-jet mode intact. The results of three nozzle designs are compared, one of which has been selected for feeding two different precursor liquids simultaneously. With three relevant sols as precursor liquids, nanostructured thin films of ZnO, ZrO2, and Al2O3 have been deposited. Their morphologies are dependent on the preparation of the precursor sols and the deposition temperature. Highly porous films were obtained by using a high deposition temperature and a sol prepared from a metal alkoxide or a metal acetate.