Jg. Fagan et al., CHARACTERIZATION OF THE TEXTURING OF YBA2CU3O7-DELTA IN THE PRESENCE OF LIQUID-PHASE ADDITIVES, Journal of electronic materials, 23(11), 1994, pp. 1103-1109
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.