FLUX-PINNING BY COLLECTIVE STACKING-FAULTS IN Y0.6HO0.4BA2CU3OY PREPARED BY POWDER MELTING PROCESS

The correlation between microstructure and flux pinning of Y0.6Ho0.4Ba 2Cu3Oy, (123) sample prepared by the powder melting process method has been investigated. Transmission electron microscopy observations show that there exists a large number of novel stacking faults (double CuO chains) in this sample. The shape of the stacking faults looks like c ollective stairs. The stacking faults are different from those observe d in the conventional melt textured 123 materials and not related to 1 23/Y2BaCuO5 interface. The sample is resintered at 900 degrees C purpo sefully in order to reduce the density of stacking faults. The magneti zation measurements indicate that the critical current density and irr eversibility lines in both field orientations (H parallel to c and H p erpendicular to c) are significantly reduced by the decrease in the de nsity of stacking faults, This means that the collective stacking faul ts work as effective pinning centers in the 123 superconductors prepar ed by the powder melting process method in a wide range of temperature s and fields. (C) 1997 American Institute of Physics.