ON A HYDRIDE 90K SUPERCONDUCTOR YBA2CU3OXHY

Hydride samples of YBa2Cu3Ox . H-y were prepared by allowing a 90K sup erconductor YBa2Cu3Ox to react with hydrogen. By the iodometric tit ra tion and magnetization measurement for hydride samples, it was shown t hat (i) an average valence number of copper decreased linearly with in creasing hydrogen content, (ii) the oxygen content x' remained unchang ed during hydrogenation, that is, x'=x, (i) critical temperature incre ased from 91.8K to 94.2K for 0 less than or equal to y less than or eq ual to 0.3 and decreased from 91.9K to 91.0K for 0.46 less than or equ al to y less than or equal to 1.4. In addition, our hydrogenated sampl es showed a transition from diamagnetic to paramagnetic, similar to on e observed in the hydrogen absorption of an alloy YM(2).