NMR Study of Hydrogen in a YBa sub 2 Cu sub 3 O sub 7-- delta Ceramic

It is well documented that H alters the high temperature superconducting properties of yttrium ceramics, and in this context, the physico-chemical state of H added to the ceramic by a treatment with water vapour, has been clarified. Broad line NMR was employed to detect the H, and X-ray diffraction to record changes in the crystalline lattice. Essentially, it is shown that the H exists in four distinct states, and these have been identified. The total number of protons in 1 g of ceramic is 4.8 x 10 exp 20 , of which > 80% are implanted in the crystalline lattice. NMR spectra of protons, recorded over a wide range of temperatures, provided evidence of the absence of paramagnetism in Cu ions. Graphs. 14 ref.--AA