AQUEOUS DEGRADATION OF BI-2212 SINGLE-CRYSTALS - AN AFM STUDY OF SURFACE ALTERATION

The early stages of environmental degradation of single crystals of Bi -based 2212 HTSC have been investigated by atomic force microscopy. Th e results show that cation exchange is the dominant mechanism, leading to extraction of alkaline earth species, formation of an amorphous su rface layer and precipitation of sub-micron carbonate crystallites. Th e absence of Cu-O chains inhibit anion exchange reactions, thus preven ting extensive network dissolution. This accounts for the greater dura bility of the Bi-based HTSCs in comparison with the 1-2-3 compounds.