Microstructures of the melt-powder-melt-growth processed YBaCuO

Microstructures of two MPMG processed YBaCuO materials with and without Y2BaCu05 (211) inclusions were investigated by transmission electron microscopy. Using the MPMG process, it is possible to change the quantity of the 211 inclusions in the YBa2Cu307 (123) matrix. We prepared two YBaCuO samples with 0 and 30 vol. % 211 and with respective critical current density values of 2000 and 30000 A/cm2 at 77 K and 1 T (magnetic field parallel to the c-axis). As possible pinning centers, we found stacking faults in the 123 matrix. However, we observed no appreciable change in their number and structure by introducing the 211 inclusions. Therefore, the difference in Jcvalues can be attributed to the 211 inclusion itself.