CHARACTERIZATION OF THE TEXTURING OF YBA2CU3O7-DELTA IN THE PRESENCE OF LIQUID-PHASE ADDITIVES

Grain growth and texturing of YBa2Cu3O7-delta is greatly influenced by the presence of liquid phase additives during sintering. Oxides such as TiO2, SiO2, Bi2O3, and Pr6O11 were incorporated into the liquid pha se during the sintering of YBa2Cu3O7-delta (123) by use of grain bound ary diffusion couples and the microstructure was analyzed using scanni ng electron microscopy/electron dispersive spectroscopy. Exaggerated g rain growth and domain formation was observed in bulk specimens. Diffe rential thermal analysis and real time dynamic x-ray diffaction were u sed to determine reaction sequencing. The ability and extent of domain formation was determined for 123 samples coupled with impurity oxides to be a function of sintering temperature (940-980 degrees) and oxyge n partial pressure. Enhanced texturing was observed at low PO2 atmosph eres. The addition of Bi2O3 and TiO2 was shown to degrade de magnetic susceptibility of 123 whereas SiO2 and Pr6O11 enhanced it. The domain formation and texturing takes place in the bulk for 123 at temperature s of 980 degrees C or below (i.e. well below the peritectic decomposit ion temperature) by the interaction of an impurity doped liquid phase followed by a precipitation and exaggerated grain growth.