Magnetization of Various Bulk Oxide Superconductors
The magnetization measurement at 77K was carried out for various bulk specimens of YBa2Cu3O7-x prepared by spray drying process.
The magnetization at low field (< 0.015 T) had hysteresis ΔM. The transport current was applied to specimens and their magnetization was measured. As the transport current was increased, the hysteresis AM was decreased. When current was over the critical current Ic of the specimen, AM did not changed with the transport current. At high field (> 0.03 T ), AM was not related to transport current. Therefore AM at high field is expected to be caused by shielding current in grains.
The effects of grain size of specimens on magnetization were studied. The hysteresis AM at low field of small grain bulk specimen was larger than the large grain specimen. And critical current Ic of small grain specimen was higher. Nevertheless the hysteresis AM at high field of the small grain specimen was smaller than the large grain specimen and it depended on magnetic field more strongly.
We prepared the bulk specimen of YBa2Cu3O7-x with Ag, using Ag2O powder. The hysteresis AM of this specimen increased by three to eight times.
KeywordsHigh Field Field Dependence Critical Current Density Transport Current Magnetic Field Dependence
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- H. Higuma, H. Nakajo, M. Wakata, and K. Egawa, Proceedings MRS,(1988)Google Scholar