Improved Fabrication of Electrophoretically Deposited Bi 2 Sr 2 CaCu 2 O 8 Films via Supporting Electrolyte Optimization in Ethanol

This paper describes the effect of the addition of supporting electrolytes sodium chloride (NaCl), potassium chloride (KCl), and lithium chloride (LiCl) on the stability of Bi2Sr2CaCu2O8 (Bi-2212) suspension for improved electrophoretic deposition (EPD) of Bi-2212 films. The optimal concentrations are found to be 7.15, 5.21, and 8.09 wt% for NaCl, KCl, and LiCl, respectively. They exhibit characteristic high zeta potential, small particle size, and low settling velocity entailing that well-stabilized Bi-2212 suspensions are produced. The resulting films possess a relatively smooth surface, high transition temperature (Tc), and high c-axis orientation. Further analysis shows that LiCl is the most suitable supporting electrolyte for the Bi-2212 suspension. The mechanism of action of this supporting electrolyte is influenced by the Hofmeister effects, which yields an electrostatic stabilization mechanism. The synthesized film using the optimal LiCl concentration demonstrates the highest Tc (87.25 K) and is c-axis oriented and well-textured.