Diffusion-couple experiments in conjunction with scanning electron (SE
M) and energy dispersive X-ray analysis were used to determine the eff
ect of various oxides on the microstructural development of YBa2Cu3O7-
x ceramic superconductors. The interaction of a number of impurity oxi
des including SiO2, Bi2O3, Pr6O11, TiO2, SnO2, In2O3 and Sb2O3 resulte
d in exaggerated grain growth and domain formation in bulk specimens t
hrough a liquid-phase wetting mechanism. Reaction sequencing was deter
mined by thermal analysis (DTA) and real-time dynamic X-ray diffractio
n. The ability and extent of domain formation for samples coupled with
SiO2, Bi2O3, Pr6O11 and TiO2 was determined to be a function of oxyge
n partial pressure during sintering as well as of the sintering temper
ature in the range 940-degrees-C-980-degrees-C. The use of Bi2O3 coupl
ed to pre-oriented samples (i.e. hot forged) resulted in extensive dom
ain growth at 980-degrees-C. The presence of SiO2 in conjunction with
hot forging resulted in a lower magnetization response, due to the pre
sence of larger 211 particles and or extensive cracking during sinteri
ng.