A new way of preparing the Y-Ba-Cu-O high-temperature superconductor using the sol-gel method

摘要

A new way of preparing Y-Ba-Cu-O (YBCO) high-temperature superconducting (HTSC) materials has been developed using the sol-gel processing technique based on new and convenient precursors that are stable in air and have high compatibility with each other. For the preparation of HTSC materials, instead of unstable copper alkoxides, the use of chelate type copper compounds as highly effective and stable precursors has been suggested. These have been prepared by the reaction of copper hydroxide with the corresponding (mono, di, tri)ethanolamines. A new method of preparing yttrium precursors on the basis of coordination acetylaceton ate type polymer has been suggested. A reaction with bidentate type complex forming solvents such as 2-alkoxyethanols results in the formation of the complex type yttrium alkoxides. Superconducting YBCO ceramic materials have been developed, both films (applied on yttrium stabilized zirconia) and powders, using the sol-gel method based on the new yttrium and copper precursors. X-ray and thermal analyses of the synthesized materials have been carried out. The transition temperature into the superconducting state, T(0)_c, and the temperature interval of this transition, DELTA T, have been found to be T(0)_C = 84 and 88 K and DELTA T = 4 and 3 K for YBa_2Cu_3O_(7-x) bulk ceramics and thin films, respectively.