The preparation of high T/sub c/ superconductors from nitrates

The preparation of high T/sub c/ superconductors, in most cases, proceeds by ceramic methodology from the metal oxides and carbonates. In this paper the authors show that the same materials can easily be derived, as well, from nitrates. Nitrates are a potentially useful class of starting materials because of their solubility and thus possible use in technologies that require the deposition of thin films of precursors to the high T/sub c/ superconductors. When the appropriate mixture of nitrate salts is prepared and ground together, then fired, first in air, and then in pure oxygen, the superconducting material results. Both the La/sub 1.85/Sr/sub 0.15/CuO/sub 4/ and Ba/sub 2/YCu/sub 3/O/sub 7/ materials have been prepared in this way. Their authenticities have been confirmed by comparison of their x-ray powder patterns and resistivity properties with those published for known materials. In addition the authors demonstrated that solutions of nitrate salts can be analyzed for purity by a simple spectroscopic method