Metal oxides are prepared from precursors that contain the metal ions as building blocks for the (multi)metal oxide to be synthesized. Precursors are made on labscale and applied for the preparation of metal oxide powders, films (with thicknesses ranging from several hundreds of nm’s down to a few nm) and patterns by means of soft lithography. Several types of chemistries are investigated, ranging from water based (multi)metal ion precursor solutions to traditional sol-gel precursor chemistry. The former shows the advantages of high stability and homogeneity using a non toxic solvent (water), while on the other hand the alkoxide based sol-gel route, applying alkanol solvents, is investigated for its low temperature oxide formation capabilities. A vast body of expertise has been built up for the preparation of aqueous precursor solutions based on carboxylato complexes of metal ions. These precursor solutions are now applied as a library, to mix and match in order to obtain most any desired multimetal oxide composition thinkable.
For all of the precursors, both chemical and structural characterization is carried out of the different stages from precursor to final oxide. The precursor starting materials and the intermediates on the way towards formation of the oxide by thermo-oxidative decomposition or hydrolysis and condensation reactions, are investigated by a range of analysis techniques including thermogravimetric analysis coupled online to MS or FTIR spectrometry, high temperature X-Ray Diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (S(T)EM) etc.
As the precursors are liquids, they are ideally suited for adaption towards printable metal oxides (see Lumoza).