Etching Behavior and Electrochemistry of a Bi-Sr-Ca-Cu-O Superconductor in Acidic Media.

Bismuth strontium calcium cuprate superconductors with nominal composition, Bi sub 2 (Sr,Ca) sub 3 Cu sub 2 O sub 8, have been examined by electrochemical techniques and are found to be both highly oxidizing compounds and reactive towards hydrogen ions. The chemical reactivity of 84K bismuth strontium calcium cuprate is similar to that of Ba sub 2 YCu sub 3 O sub 7 . The dissolution reaction in acid is intrinsically fast; we observe H sup + mass transport control in perchlorate solution. Dissolution rates can be altered and made selective by surface filming and post reactions of Bi sup (+3) , as in Cl sup - solution. The stoichiometries of the acid reactions and for the etching of the Bi sub 2 (Sr,Ca) sub 3 Cu sub 2 O sub 8 by ethylenediaminetetraacetate have been determined by rotating ring-disk methods. Several etching solutions readily adaptable to controlled patterning or removal of these substrates have been demonstrated.