EFFECT OF Y2BACUO5 AND PTO2-CENTER-DOT-H2O ADDITIONS ON THE MICROSTRUCTURAL DEVELOPMENT IN YBA2CU3O7-DELTA SUPERCONDUCTORS

Results are presented concerning the formation kinetics of Y2BaCuO5 (2 11) and YBa2Cu3O7-delta (123) phases during melt processing of melt qu ench (MQ) precursors and phase pure 123. The influence of Pt and 211 a dditions on the microstructural development within YBa2Cu3O7-delta sys tem are examined quantitatively via XRD analysis and DTA. Real time dy namic XRD analysis showed the phase reaction sequences for the MQ and phase pure 123 (SSC) percursor systems, and activation energy (E(a)) f or 211 formation to be lower for MQ powders upon peritiectic decomposi tion. The SSC precursors developed greater amounts of 211 at 1100 degr ees C when compared to MQ precursors, (similar to 28 wgt % vs. 10 wgt % respectively). The addition of 0.5 mol percent (m/o) Pt resulted in higher E(a) for 123 phase formation with higher solidification tempera tures when added to SSC powders. The use of 5 m/o 211 additions in SSC resulted in lower 123 solidification temperatures and E(a) than that without 211 addition Pt additions did alter the residual 211 content u pon texturing. The presence of Pt with excess 211 additions was seen t o inhibit 211 formation upon texuting.