Sol-gel processing of Y1Ba2Cu3O7-x using alkoxide precursors: two systems yielding high degrees of thin film orientation and crystal growth

An alkoxide sol-gel chemistry has been developed to form superconducting Y1Ba2Cu3O7-x thin films and bulk powders. The Cu(II) ethoxide synthesis and processing steps used to obtain a homogeneous Y-Ba-Cu sol are specifically outlined. Sols were produced using two different solvent systems: toluene and methoxyethanol/methylethylketone. Both systems promote complexation of insoluble Cu(II) ethoxide with the barium and yttrium precursors allowing the formation of nanometer-sized sols. Thermal gravimetric analysis and differential thermal analysis were used to characterize the gel decomposition and oxide formation processes. The toluene system produced gels having a crystallization temperature of 4250C while the methoxyethanol/methylethylketone processed gel crystallized at 5000C. The methoxyethanol/methylethylketone gel had essentially complete organic by-product oxidation by 4750C. Films produced on single crystal SrTiO3 (for both systems) showed a high degree of orientation and crystal growth. 7 refs.; 10 figs.; 1 table