Pre-sintering densification phenomenon of YBa2Cu3O7−y in the presence of non-equilibrium Ba-Cu-O compounds

The dynamic sintering behaviour of YBa₂Cu₃O_7-y containing Ba-Cu-O and other nonequilibrium impurity phases was investigated through dilatometry. It revealed the occurrence of subsidiary shrinkage just prior to the solid-state sintering. Densification tests also showed a rapid increase in the apparent density in the temperature range between 920 and 940 °C. X-ray diffraction analysis and optical microscope observations verified the correlation with the Ba-Cu-O phases. The phenomenon was attributed to the effect of rearrangement densification exerted by the transient liquid from Ba-Cu-O and to the reaction sintering densification when Ba-Cu-O reacts with other phases during heating.