HYDROGEN-ABSORPTION EFFECT ON YBA2CU3OX

Hydrogenated samples of YBa2Cu3Ox'Hy were prepared by allowing an oxid e superconductor YBa2Cu3Ox to absorb hydrogen. From magnetization meas urements, it was shown that the critical temperature increased from 91 .8 K to 94.2 K for 0 less-than-or-equal-to y less-than-or-equal-to 0.3 and decreased from 94.0 K to 91.9 K for 0.4 less-than-or-equal-to y l ess-than-or-equal-to 1.4. The iodometric titration indicated that an a verage valence number of copper decreased linearly with increasing hyd rogen content. The hydrogenated samples displayed superconductivity ab ove 90 K even when the average valence number of copper was below 2.0. Consequently it was concluded that the oxygen content remained at its initial value of 6.98 even though the oxide superconductor had absorb ed hydrogen.