DEGRADATION OF SINTERABILITY AND SUPERCONDUCTING PROPERTIES OF FINE PARTICLE YBA2CU3O7-Y BY EXPOSURE TO MOISTURE

The effect at room temperature of ambient level humidity on fine particle YBa2Cu3O7-y powder has been studied. Reaction with moisture, as detected by x-ray diffraction and scanning electron microscopy, was found to proceed rapidly initially (<48 hours), but then became quite slow. The sinterability and the superconducting properties (magnetic flux exclusion) of the powder also degraded rapidly at first, while subsequent degradation was relatively slow, suggesting that surface reaction products are responsible for property degradation. The lower sinterability was the result of two contributions: (1) lower green density due to increasing agglomeration and (2) lower surface reactivity with regard to sintering. Suggestions are presented for minimizing the presence of moisture by processing the superconducting oxide in an appropriate non-aqueous solvent.