On a hydride 90K superconductor YBa2Cu3OxHy

Hydride samples of YBa2Cu3Ox•Hy were prepared by allowing a 90K superconductor YBa2Cu3Ox to react with hydrogen. By the iodometric tit ration and magnetization measurement for hydride samples, it was shown that (i) an average valence number of copper decreased linearly with increasing hydrogen content, (ii) the oxygen content x′ remained unchanged during hydrogenation, that is, x′ = x, (iii) critical temperature increased from 91.8K to 94.2K for 0≦y≦0.3 and decreased from 91.9K to 91.0K for 0.4≦y≦1.4. In addition, our hydrogenated samples showed a transition from diamagnetic to paramagnetic, similar to one observed in the hydrogen absorption of an alloy YM2.