J. Phys. I France
Volume 2, Number 1, January 1992
Page(s) 63 - 67
DOI: 10.1051/jp1:1992123
J. Phys. I France 2 (1992) 63-67

Some diffusive properties of oxygen in Y-Ba-Cu-O systems

D. Djurek1, V. Manojlovic1, Z. Medunic1, M. Prester2, E. Babic3 and K. Zadro3

1  Volta Applied Ceramics, 41000 Zagreb, Croatia, Yugoslavia
2  Institute of Physics of the University of Zagreb, 41000 Zagreb, Croatia, Yugoslavia
3  Department of Physics, Faculty of Natural Sciences, 41000 Zagreb, Croatia, Yugoslavia

(Received 21 August 1991, accepted 4 October 1991)

We have studied the diffusive properties of oxygen in Y-Ba-Cu-O systems at 940  $^{\circ}$C by measurements of the resistive response time $\tau$ of the samples subjected to the step-like increase of the oxygen pressure $\Delta p_{{\rm O}_2}\sim 1$ to 5 bars. The superconducting (SC) transition widths $\Delta T_{\rm c}$ plotted versus inverse diffusion constant $D^{-1}\sim\tau$ obey the universal linear dependence. The characteristic protruded tail of the real part of AC susceptibility which exhibits the feature at 86 K is absent in samples with the nominal composition Y 3Ba 3Cu 6O x (Y-336) in the regime $\tau<3$ s as result of weakly connected grains of YBa 2Cu 3O $_{7-\delta}$ (Y-123) nucleated from decomposed Y-336 phase.

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