ENVIRONMENTAL DEGRADATION OF YBA2CU3O7-X - A DESCRIPTIVE AND PREDICTIVE MODEL

The relationships between the formation of an amorphous surface layer, generation of planar defects, and the surface reactivity during the e arly stages of degradation of the 1-2-3 compounds have been examined. It is found that these microstructural attributes of the degradation p rocess promote the enhanced rates of aqueous attack which lead to netw ork breakdown and total dissolution during subsequent stages. The tota lity of information on the degradation processes has been incorporated into an overall model which predict that c-axis textured 1-2-3 films and the Bi/Tl system should be relatively more durable.