Stoichiometric variations of Bi 2212 electrophoretically deposited thick films

Thick films of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ have been manufactured from a variety of starting powders. The prime objective of this study is to keep the density of large secondary phases to a minimum whilst not disturbing the processability of the superconductor. This work focuses on changes in source powder composition. We have found that very small changes in stoichiometry can affect the melting behaviour and J/sub c/ of the films, and the density of alkaline earth cuprate phases. It was found that powder sold as "partially reacted" (annealed at 800/spl deg/C) was best, and that using this production route, powder with a slight deficiency in either Ca or Cu gave the highest J/sub c/ values, exceeding 8000 A cm/sup -2/, in self-field at 77 K.