Precursor homogeneity and crystallization effects in chemical solution deposition-derived alkaline niobate thin films

Chemical solution deposition-derived potassium niobate and sodium niobate thin films have been prepared under protective atmosphere using an alkoxide approach. A profound dependency of the quality and homogeneity of the resulting thin films on the preparation of the alkaline precursor has been found. In addition to this, an additional increase in microstructure homogeneity for the significantly more sensitive potassium niobate system is obtainable if the precursor solution is further stabilized by acetylacetone although ambient humidity is already strongly suppressed. The observed behavior is attributed to the stabilization of the heterometallic complex in the precursor solution until film deposition commenced. Further on, the crystallization pathway of the respective alkaline niobate thin films has been evaluated and indication of crystallization through a metastable phase has been provided which seems to play a key role in orientation control. Finally, the temperature dependency of the lattice parameter spacing for potassium niobate and sodium niobate thin films has been presented and evidence of a strong substrate-induced lattice deformation has been given. © 2011 The American Ceramic Society