Hydrothermal, Hydrothermal-Electrochemical and Electrochemical Synthesis of Highly Crystallized Barium Tungstate Films

Highly crystallized polycrystalline films of BaWO4have been synthesized on tungsten metal substrates by hydrothermal-electrochemical and electrochemical methods from room temperature to 200 °C. The hydrothermal method did not produce a film because only discrete BaWO4particles appeared on the tungsten substrate. The crystallization of BaWO4was characterized by three-dimensional nucleation and growth behaviors. In the case of the electrochemical method, an amorphous tungsten oxide film formed after the BaWO4film formation, while the hydrothermal-electrochemical method did not produce an amorphous film.