Effect of Y/sub 2/BaCuO/sub 5/ and PtO/sub 2/·H/sub 2/O additions on the microstructural development in YBa/sub 2/Cu/sub 3/O/sub 7-δ/ superconductors

Abstract

Results are presented concerning the formation kinetics of Y2BaCuOg (211) and Y BaaCu307 4 (123) phases during melt processing of melt quench (MQ) precursors and phase pure 123. The influence of Pt and 211 additions on the microstructural development within YBa2CujO.I -6 system are examined quantitatively via XRD analysis and DTA. Real time dynamic XRD analysis showed the phase reaction sequences for the MQ and phase pure 123 (SSC) percursor systems, and revealed the activation energy (&) for 211 formation to be lower for MQ powders upon peritiectic decomposition. The SSC precursors developed greater amounts of 211 at llOO°C when compared to MQ precursors, (-28 wgt % vs. 10 wgt % respectively). The addition of 0.5 mol percent ( d o ) Pt resulted in higher E, for 123 phase formation with higher solidification temperatures when added to SSC powders. Tbe use of 5 m/o 211 additions in SSC resulted in lower 123 solidification temperatures and E, than that without 211 addition. Pt additions did alter the residual 211 content upon texturing. The presence of Pt with excess 211 additions was seen to inhibit 211 formation upon texuting. 0 1995 IEEE