Diffusion of oxygen in superconducting YBa2Cu3O7−δ ceramic oxides
K. N. Tu, N. C. Yeh, S. I. Park, C. C. Tsuei
DOI 10.1103/PhysRevB.39.304 · Physical Review B
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Abstract
We have used in situ resistivity measurements to monitor the diffusion of oxygen in and out of the ceramic oxide YBa2Cu3O7−δ. The study of out-diffusion of oxygen was carried out by annealing the oxide in ambient helium at constant heating rates and at constant temperatures. The rate of out-diffusion of oxygen has been found to be independent of δ, and the resistivity changes linearly with time during isothermal anneals. Assuming that the rate of out-diffusion is surface reaction limited, we have determined a surface barrier of 1.7 eV. The study of in-diffusion of oxygen was performed by annealing the oxygen-deficient oxide (δ=0.38) in ambient oxygen. The in-diffusion rate was found to depend strongly on δ; we have determined the activation energies of the process at δ=0.38 and δ=0 to be 0.5 eV and 1.3 eV, respectively. The diffusivity of oxygen for δ=0 has been determined to be D=0.035exp(−1.3 eV/kT) cm2/sec. Combining the kinetic data and published structural information, we have examined a vacancy mechanism and a twinning mechanism for anisotropic diffusion of oxygen in the CuO layer between the BaO layers.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| YBa2Cu3O7-δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 91 | Pressure not reported | zero_resistance |
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