New observations related to hydrogenation of YBa2Cu3O7-δ (YBCO) are reported: (a) The effects of sample preparation on the H concentration in "uncharged" YBCO samples is investigated, and it is shown through nuclear magnetic resonance measurements that samples of YBCO prepared by "standard" solid-state reaction procedures may contain ab initio up to 0.2 atoms formula-1 of hydrogen. (b) It is demonstrated that one may introduce up to 0.3 atoms formula-1 into single crystal samples of YBCO without destroying the macroscopic crystal. The significance of the above observations is discussed briefly.
Bibliographical noteFunding Information:
Helpful discussions with S. Goren and I. Felner are gratefully acknowledged. We are indebted to S. Goren for making available some of his recent results before publication, and to Michal Rokni for providing us the YBCO samples of Batch 2. This work was supported in part by the Israel Ministry of Science and Technology (Grant No. 3198) and by the Klachky Foundation for Superconductivity.