Electrochemical synthesis of barium titanate thin films

Polycrystalline films of barium titanate (BaTiO3) have been synthesized on titanium (Ti) substrates by the galvanostatic anodization of Ti in a solution of 0.4 M Ba(OH)(2). Crystalline films are formed al temperatures under 100 degrees C within 10 min at a current density of 25 mA/cm(2) at atmospheric pressure, Crystallinity of the films is found to increase with both current density and time of reaction. At 90 degrees C, a film of 1 mu m thickness is formed after 10 min; grain sizes up to 0.5 mu m are obtained. Microstructure of the films is found to be critically dependent on the pretreatment of the titanium anode, Capacitance measurements on the film yield a dielectric constant of 200 with a minimum tan delta of 0.09 at 10 kHz. On the basis of the voltage-time curves, it is interpreted that an amorphous intermediate is formed which crystallizes to form perovskite BaTiO3.