PhysicaC 176 (1991) 216-226 North-Holland Preparation and characterization of textured thick films of the 22 12 phase in the BSCCO and BPSCCO systems L. Dimesso, M.G. Francesconi and G. Calestani Institute di Strutturistica Chimica, Universita di Parma and Centro di Studio per la Strutturistica Diffiattometrica de1 CNR, Viale delle Scienze, I-43100 Parma, Italy E. Silva, R. Fastampaand R. Marcon Dipartimento di Fisica, Universita di Roma La Sapienza-Roma I-00185, and Gruppo Nazionale di Struttura della Materia del CNR, Roma and Centro Interuniversitario di Struttura della Materia de1 Minister0 U.R.S. T., Roma, Italy D. Fiorani, E. Agostinelli and A.M. Testa I.TS.E.-C.N.R. Area della Ricerca, P.B. 10, I-00016 Monterotondo Stazione, Italy Received 17 January 199 1 Revised manuscript received 18 March 199 1 The preparation of textured thick films of the 22 12 phase in the BSCCO and BPSCCO systems by a partial melting process of powders deposited on Ag substrates by drying alcoholic suspensions is reported. The quality of the films in the BPSCCO system can be improved as far as microstructure and electrical properties is concerned, by starting from non-stoichiometric compositions, in particular by adding PbO to 2212 BSCCO powders. The influence of the PbO addition on structural, electrical and magnetic properties is discussed. Very high critical current densities (5 x 1 06-9x lo6 A cm-’ at 10 K and for H= 5 kOe), comparable to or quite greater than those reported for single crystals, can be obtained by this new preparation method. 1, Introduction The Bi-Sr-Ca-Cu-0 and Bi-Pb-Sr-Ca-Cu-0 superconductors (BSCCO and BPSCCO respec- tively) are characterized not only by their high tran- sition temperatures (T,) but also by high critical magnetic fields [ 11. These features make them in- teresting for technological applications at 4.2 K and high field regime (> 20 T); in such conditions no conventional superconductor is available. For these applications textured materials are required, since the critical current density (Jc) depends critically on the microstructure because of the two-dimensional- ity of these systems. Various rapid solidification techniques can be ap- plied for the fabrication of B&based superconducting wires and/or tapes [ 2-41. Among them, the melt quenching method is promising for obtaining a high- T, superconducting film. In fact, the increased den- sification and homogeneity of the materials may in- crease the critical current density to higher values than those obtainable by a conventional preparation method [ 5 1. In spite of the incongruent melting of the 2212 phase, aligned microstructures could be obtained by a growth method from partially molten oxides [ 6,7]. More recently, textured tapes of BizSrzCaCu20, on Ag substrate have been prepared [8-l 0 ] by com- bination of doctor-blade casting and crystal growth from the melt and very high critical currents ( lo5 A/ cm2) were reported. However, the process leading to the crystallization of 2212 from the melt in almost single phase was not completely clarified. Moreover, it was shown [ 11,121 that 2212 single crystals in the BPSCCO system can be grown from non-stoichiometric melts, in a way similar to the cor- responding BSCCO; the T, seems to depend on the lead content (it can result in a T, up to 10 K higher) 0921-4534/91/$03.50 0 1991 - Elsevier Science Publishers B.V. (North-Holland)