Rheological study of a gel-forming precursor for superconducting YBa2Cu3O7-x

Khan, Saad A.; Barboux, P.; Bagley, B. G.; Tarascon, J. M.
August 1988
Applied Physics Letters;8/22/1988, Vol. 53 Issue 8, p700
Academic Journal
Rheological measurements are used to monitor the sol-gel behavior of a superconducting precursor. A precursor made with an aged yttrium component [Y(OH)3] has a much higher elastic modulus (G’) and complex viscosity (η*) but the same loss modulus (G‘) compared to that made with a fresher yttrium solution. The G‘/G’ ratio is less than unity for the older solution but greater than 1 for the fresher sample, indicating that the former solution has a more gel-like character. The high viscosity sample gives better fired thick-film superconducting properties but has a shorter shelf life. Measurements on yttrium components of different age show differences in viscosity and G‘/G’ which correlate with the behavior of the oxide precursors. Reshearing the precursor solution at any stage during its gelation process can cause irreversible changes in the gel structure.


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