The relation of YBa/sub 2/Cu/sub 3/O/sub 7-x/ properties to densification technique

High bulk density samples of YBa/sub 2/Cu/sub 3/O/sub 7-x/ ceramic have been fabricated from mixed oxide powders by sintering, hot pressing, and sinter forging. Utilizing 1-2-3 powders (calcined mixtures of Y/sub 2/O/sub 3/, Ba(NO/sub 3/)/sub 2/, and CuO), sample densities of 92-93% of theoretical for sintering and 96-97% for hot pressing and sinter forging have been achieved. In all cases, oxygen annealing after densification was required to obtain orthorhombic 1-2-3. Grain orientation factors (f), as determined by x-ray diffraction, show only slight orientation for sintered and hot pressed samples (f = 0.11 - 0.19). However, high density sinter forged samples showed significant orientation (f = 0.54). Grain orientation was also reflected in the anisotropic magnetic response to an applied field. For measurements taken with the field along the forgoing direction, expulsion (Meissner) values were 2.5 X greater than those measured with the magnetic field perpendicular to the forging direction. Similar but smaller anisotropy was measured for the hot pressed samples