BACUO2-AG INTERACTION - A CENTRAL FEATURE IN THE DENSIFICATION OF AG-Y1BA2CU3O7-DELTA COMPOSITES

Dilatometric and DTA / TGA measurements (in O-2 atmosphere) on Ag-123 composites indicate that silver affects dramatically the two principal reactions that provoke the unstabilization of Y1Ba2Cu3O7.delta. These are the precipitation of 011 phase plus Yttrium rich liquid (900-930 degrees C), and the peritectic reaction triggered by 011 fusion(980-10 40 degrees C). Silver increases, upon initial heating, the partial dec omposition of 123 phase (ER). For pre-peritectic temperatures higher t han the Ag-AgO eutectic temperature, it interacts with 011 phase for d eveloping a ''re-assembling mechanism''. A modified 123 phase named 12 3 levels of Ag, possibly as a layer of 123* around 123 grains. SEM / EDAX analysis show the superficial nature of the re-assembling phenome na.