The reactivity of sintered samples of YBa2Cu3O7-y with moisture at elevated temperatures has recently been reported . The reaction sequence proposed was:
Such instability of the 1–2–3 phase has serious implications regarding not only the use of the sintered material, but powder processing as well. While the need for fine particle 1–2–3 powder exhibiting good sinterability is recognized, it is also anticipated that the degradation of this material will accelerate with decreasing particle size because of the larger surface area. Thus, we have conducted a series of experiments to monitor the effect of ambient atmosphere on fine particle 1–2–3 powder. The powder was monitored as a function of time by x-ray diffraction, scanning electron microscopy, sintering characteristics and magnetic flux exclusion.