Molybdenum-based mixed oxides for sensing applications: effect of the Molybdenum composition on the structure of sol-gel thin films

In this work, we report on the structural investigation by transmission electron microscopy of molybdenum-based mixed oxides for use as gas sensitive films. In particular, sol–gel thin films of molybdenum–titanium and molybdenum–tungsten oxides, deposited by spin coating on silicon substrates, have been analyzed by selected area electron diffraction, conventional, and high-resolution transmission electron microscopy. Our results show that the relative percentage of the molybdenum precursors used during the sol–gel deposition controls the morphology of the films, by modifying the size and the arrangements of the polycrystalline grains on the substrate.