Abstract

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 at temperatures under 100 °C within 10 min at a current density of 25 mA/cm2 at atmospheric pressure. Crystallinity of the films is found to increase with both current density and time of reaction. At 90 °C, a film of 1 μm thickness is formed after 10 min; grain sizes up to 0.5 μm 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.

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