Preparation of bulk and thick films of YBa2Cu3O(7-y) using a solution technique

The high Tc superconducting oxide YBa2Cu3O(7-y) has been synthesized using a solution technique, and the resultant properties are compared to materials synthesized by solid state reactions. Because the cations are mixed at the microscopic level, this solution technique allows lower reaction temperatures and shorter reaction times to obtain the superconducting material. They yield materials with particle sizes of about 1 micron and having a narrow size dispersion (as compared to the typically 50 microns particle sizes obtained by solid state reactions). The smaller, uniform particle sizes yield denser compacts upon sintering. Densities of 90 percent have been achieved, and metallic-like behavior improves and is correlated with increasing density. The solution derived materials superconduct at 91 K and have narrow transition temperatures (0.6 K width) which is attributed to sample compositional and structural homogeneity. Because stable, viscous gels have been produced, the preparation of large area thick films on various substrates of technological interest (e.g., alumina, zirconia, strontium titanate) has been investigated. 9 references