Synthesis and characterization of barium titanate films on Ti-coated Si substrates by plasma electrolytic oxidation

Barium titanate (BaTiO3) films were synthesized on Ti/Si substrates by plasma electrolytic oxidation using 0.5 M Ba(OH)2 as the electrolyte. A potentiostatic mode with the voltages ranging from 30 to 70 V was used to synthesize the films. X-ray diffraction results show that cubic BaTiO3 films were successfully produced on Ti/Si substrates. From analyses of the induced currents, the occurrence of spark discharge, and the surface morphology, it is found that electrochemical oxidation occurred at voltages below 40 V, while plasma electrolytic oxidation predominated at voltages above 60 V. A mixed electrochemical oxidation and plasma electrolytic oxidation regime was present at voltages between them. The BaTiO3 films made by PEO exhibited better corrosion properties than those of synthesized by electrochemical oxidation. The dielectric constant increased with the increasing reaction voltages, due to the formation of thick and dense BaTiO3 films.