New Microcrack Network Generation in TSMTG YBCO

Melt Textured YBa2Cu3O7/Y2BaCuO5 (Y123/Y211) and Y123/Y211/CeO2 composites, have been grown by Top Seeding Melt Texturing growth (TSMTG). The initial powder mixture has been densified, through a pre-melting process carried out at 1000-1050 degrees C under O-2 atmosphere. This process leads to a strongly decreased porosity of the pellet. Afterwards, TSMTG is carried out in air atmosphere. The influence of the pre-melting process on the final microstructure has been analyzed by optical and scanning electron microscopy (SEM). Microstructural analysis reveals a high microcracking density. Three well defined microcrack orientations have been detected, one parallel the (001) planes and a new class of microcrack parallel the {100} planes. The latter is being produced by the pre-melting densification process, while the usual microcrack parallel to (001) planes also prevail. The influence of the oxygenation process and the Ce additives on the development of this new class of microcrack pattern will be discussed. Finally, the influence of the new microcrack network on the critical current density will be presented.