Effect of Y2BaCuO5 Particles on Pinning Characteristics of Y-Ba-Cu-O Prepared by Melt Powder Melt Growth Method

Two kinds of YBaCuO bulk samples with different densities and sizes of 211 particles were prepared by the melt powder melt growth method. The magnetic field and temperature dependences of critical current density, J c, were measured inductively. Strong dependence of J c on size and density of 211 particles at higher temperatures was observed, while no relationship could be recognized between the two at lower temperatures. This result supports the expectation that nonsuperconducting particles such as the 211 phase act as dominant pinning centers at higher temperatures. A history effect was observed at 4.2 K, suggesting an existence of weak links.