Barium titanate films synthesized by an anodic oxidation-based electrochemical method

Barium titanate films were synthesized by anodic oxidation galvanostatically in an electrolyte of 0.5 M Ba(CH3COO)2 with 2 M NaOH. The films were first prepared using a wide constant current range from 5 to 40 mA. XRD results showed that rutile TiO2 was present at 10 mA and cubic BaTiO3 films could be obtained at currents over 20 mA. The Ti anodes were then electrolyzed at constant current of 30 mA with various deposition times from 0.5 to 4 h. XRD results showed that TiO2 existed at 0.5 h and BaTiO3 appeared at electrolytic times over 0.75 h. From the XRD results associated with the variations of electrolytic voltage with time, rutile TiO2 has been found to be a precursor for the formation of BaTiO3. BaTiO3 films with uniformly distributed small grains were formed at voltages over 60 V and below the dielectric breakdown voltage. The formation mechanism could be due to dissolution and crystallization. BaTiO3 films with large crater shaped grains were present when voltages reached a dielectric breakdown voltage, which could be due to anodic spark deposition.