engleski

Critical currents and differential resistance of YBA2CU3O7-X superconducting ceramics

Transport critical current density (Jc) and differential resistance of several YBaCuO samples have been measured in the temperature range 77–91K and in the weak magnetic fields (H⩽ 150 Oe). At all fields and temperatures Rf exhibits a S-shape variation with current. For the well-prepared low- resitivity samples Rf reaches in the linear V-I regime a value of 0.15Rn, Rn being the normal resistance just above the transition, consistent with picture of the decoupled superconducting grains. Because of self-field effects, J obtained from transport (and magnetization) measurements does not provide useful information on the nature of intergrain coupling. The distributions of critical currents (d2V/dl2 vs. I) seem to rule out larger enhancement of Jc in sintered samples.

superconducting ceramics ; critical currents

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