A facile fabrication route to tungsten oxide films on ceramic substrates

Crystalline films of WO 3 were directly fabricated on alumina and zirconia ceramic substrates via a facile hydrothermal fabrication process using an aqueous peroxy-tungstate solution. The process utilized kinetically controlled decomposition reaction of the peroxy-tungstate solution to tungsten oxide following supersaturation and heterogeneous nucleation at the surface of the substrates. The films possessed remarkably different microstructures depending on the reaction conditions, but all particles were oriented normal to the substrates. X-ray diffraction, transmission electron microscopic and Raman spectroscopic data indicated that the WO 3 film had a hexagonal structure and film orientation. The WO 3 films showed a rapid gas response to NO 2 of ppm level. The data contribute to the development of film fabrication methods of a variety of oxide gas sensing elements.