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An EPR study of the effect of water vapor on the superconductor YBa 2 Cu 3 O y

1990; Elsevier BV; Volume: 76; Issue: 4 Linguagem: Inglês

10.1016/0038-1098(90)90661-t

1879-2766

Zheng‐Jun Zhou, Howard Shields, R. T. Williams, G. Eric Matthews, J.M. Williams, W Catesby Jones, R.D. Eyster,

Magnetic properties of thin films

The interaction of water vapor with freshly prepared bulk YBa2Cu3Oy produces an increase in the number of EPR active Cu2+ ions. For many of the samples studied, the number increased by a factor of about 5. On further exposure to water vapor, the number decreases to approximately its initial value. We suggest that the increase and decrease of the Cu2+ signal is due primarily to residual BaCuO2. The changes in the EPR spectra of BaCuO2 when exposed to water vapor are similar to those observed for YBa2Cu3Oy. These changes occur during the initial stage (first few hours) of exposure to 100% water vapor in air. A different Cu2+ signal is observed from samples soaked in water, probably from the production of Y2BaCuO5.