Effect of Potassium Chloride as a Supporting Electrolyte on the Dispersion Towards the Fabrication of Films by Electrophoretic Deposition of Bi 2 Sr 2 CaCu 2 O 8 in Ethanol

Bi2Sr2CaCu2 O 8 (Bi-2212) powder was fabricated using solid state reaction method. The suspensions were prepared containing finely ground Bi-2212 powder with and without potassium chloride (KCl) addition. Settling experiments and measurements of zeta potential, particle size distribution, and electrophoretic mobility were performed to determine the optimal concentration of the supporting electrolyte. Bi-2212 suspensions were used in electrophoretic deposition (EPD), and the films were heat treated. The results showed that the optimal concentration of KCl is 5.21 wt %. The zeta potential at this concentration is highest at about 31.10 mV, the settling velocity is lowest ∼3.84 mm/min, and the particle size is smallest (∼450 nm), which indicate that the dispersion is better due to the reduction of intermolecular attraction. The effects of KCl as a flux were observed in the microstructure and superconducting properties of Bi-2212 film. The smoothest surface morphology, high c-axis orientation, and highest critical temperature (T c )-onset of 84.73 K were obtained from the film prepared with optimized Bi-2212 suspension.