Sol-gel preparation of high-T c Bi-Ca-Sr-Cu-O and Y-Ba-Ca-O superconductors

High-Tc superconducting oxides have been prepared by a liquid-mix technique using etylene-diamine-tetra-acetic acid (EDTA) as a complexing agent. Bi-Sr-Ca-Cu oxides and Y-Ba-Cu oxides were made using this technique giving a better compositional homogeneity, a more precise control of the cation stoichiometry and a decreased firing temperature as compared to conventional material produced by a solid-state reaction. This technique extends the amorphous citrate process to those systems where no citrate complex exists. EDTA binds with most metallic elements of the periodic table, making this technique a versatile tool in the production and study of these new ceramic materials. Therefore, the method is easily adapted to the preparation of new superconducting oxides.