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. The results show that cation exchange is the dominant mechanism, leading to extraction of alkaline earth species, formation of an amorphous surface layer and precipitation of sub-micron carbonate crystallites. The absence of CuO chains inhibit anion exchange reactions, thus preventing extensive network dissolution. This accounts for the greater durability of the Bi-based HTSCs in comparison with the 1-2-3 compounds.