Nanostructured ceramic thin films and membranes are used for protective or functional
purposes and prepared on dense or porous substrate materials. Wet chemical methods enable
cheap, low-temperature, mass-scale manufacturing routes. They produce fine-grained porous and
dense micro-structures that cannot be realized otherwise. In wet-chemical processing, clean
nanoparticle dispersions are deposited on the substrate at, primarily, ambient conditions. The
deposition is followed by a (rapid) thermal processing treatment to remove liquids and organic
additives, to convert precursors to the target composition, and to establish the final porous and
dense micro-structure. In the synthesis of precursor dispersions it is very important to obtain
nanoparticles with a near-isometric shape and a fairly narrow particle size distribution, without the
formation of secondary (agglomerate) structures. In particular the latter requires careful control of
solution and interfacial chemistry to achieve proper colloidal stability, during and after the
synthesis process. Characterization of coating integrity, defect morphology and defect population
is done by decoration methods, microscopy, ellipsometry and statistical methods that employ
membrane transport properties.
