Flux growth of Bi-Sr-Ca-Cu-O (2212) single crystals with temperature cycling

Abstract

The growth of Bi₂Sr₂Ca₁Cu₂O_y (Bi 2212) single crystals from high-temperature solutions has been done using either self-flux or alkali halide fluxes. These were aimed at optimizing its growth parameters as well as the production of single crystals of appropriate dimensions for proper characterization. At present, the largest Bi 2212 single crystals reportedly grown using the flux method are merely platelets that average around 10 mm² x 10 μm in dimensions. In this study, the solubility curve of the 2212 pseudobinary system of Bi and KCl was initially constructed in order to approximate the metastable regions vital for nucleation. The usual slow cooling processes that included temperature cycling and an isothermal step were used. Kinetic variables were estimated using the Arrhenius relation and the two-dimensional nucleation theory. The following assumptions are adopted: (1) thermal diffusivity exceeds mass diffusivity by 10³ so that heat dissipation is rapid and an isothermal solution is a valid approximation; and (2) diffusion in the solution is the rate-limiting step, which implies that reaction kinetics and diffusion through the product layer are negligible.