1ST TIME IN-SITU INVESTIGATION OF 2223 FORMATION MEASURED ON (BI,PB)2SR2CA2CU3O10-FILMS ON AG TAPE PREPARED BY THE SCREEN PRINTING TECHNIQUE(X THICK)

Detailed investigations were performed on the reaction kinetics of the superconducting BPSCCO 2223 phase in order to be able to improve tape processing and critical current density J(c) of 2223 layers on Ag tap e made by the organic binder method. The J(c) values presently vary be tween 6- 12 x 10(3) A/cm2 (77 K, 0 T). To our knowledge, it is the fir st time that the formation of the 2223 has directly been observed empl oying in-situ high temperature X-ray diffraction (HTXRD). This measure ment was carried out on screen printed samples of BPSCCO on Ag foil he ated in a specially designed closed crucible preventing the evaporatio n of lead. The main findings are that the 2223 phase arises from the 2 212 phase at 820-835-degrees-C within a short timescale of about 2-3 h . These results were correlated with measurements on a Simultaneous Th ermal Analysis (STA) showing endothermic reactions which indicate the starting of partial melting at about 825-836-degrees-C. According to t he literature we found that the reaction kinetics are controlled by di ffusion processes under the presence of partial melt.