Production of Ba(Zr,Ti)O3 coatings on ternary (Ti,Zr)N thin film electrodes by plasma electrolyte oxidation

Abstract

Cubic perovskite barium zirconate titanate [Ba(Zr,Ti)O3; BZT] coatings were produced over ternary (Ti,Zr)N seeding layers by plasma electrolytic oxidation (PEO). (Ti,Zr)N thin films serving as the working electrode were deposited on Si substrates by unbalanced magnetron sputtering. PEO was conducted in the alkaline electrolytes consisting of 0.5 M Ba(OH)2 with a potentiostatic power mode at applied voltages ranging from 30 to 80 V for 30 s. Spark plasma discharges occurred over the thin film electrodes at reaction voltages above 50 V, characterized as a PEO regime. Sintered-like BZT coatings with porous morphology were obtained. The PEO-produced coatings exhibited substantially higher integrated diffraction peak intensities and growth rates, compared to the electrochemically oxidized coatings synthesized at lower applied voltages. X-ray photoelectron spectroscopy revealed chemical compositions of the BZT coatings. This clearly demonstrates that crystalline BZT coatings could be facilely produced over complex (Ti,Zr)N seeding layers by PEO. Possible reaction routes and formation mechanisms of the coatings were also proposed. The PEO-made BZT coatings have great potential for many dielectric and ferroelectric applications.