A facile and cost-effective approach for the fabrication Bi_0.5Na_0.5TiO₃ thick films on flexible substrate for energy storage capacitor applications

The current research reports a facile and cost-effective technique for the deposition of functional ceramics Bi_0.5Na_0.5TiO₃ thick films on flexible, low cost, electrically integrateable Ni substrate by using electrophoretic deposition (EPD) technique. EPD is a well-known, eco-friendly process for depositing coatings on a conductive substrate from a colloidal suspension. A reliable approach was adopted for stable colloidal suspension of BNT particles during conventional solid-state synthesis process by using high energy ball milling in acetone medium without the complications of surfactants and expensive platinum substrate. BNT films with thickness ranging from ~55 to 165 μm were successfully obtained by exploring EPD parameters i.e. voltage from 100 to 125 V and coating time from 30 to 240 s. Thick coatings with comparatively better adhesiveness were deposited at 100 and 125 V with coating time up to 90 s. Thick films were densified by sintering at 1150 °C for 30 min. Phase analysis were conducted by using X-Ray diffraction (XRD), Fourier transformed infrared spectroscopy and Raman spectroscopy. XRD analysis revealed the formation of single (111) peak indicating the pure perovskite structure of BNT thick film. Scanning electron microscope studies indicated that dense and uniform microstructure was obtained by EPD coating with the film thickness of ~93 μm. Impedance spectroscopy confirmed two electrically active regions of grain interior and grain boundaries.