In this paper we are reporting a study of the effect of Cs doping on the crystal structure and superconducting (J$_{c}$, T$_{c}$.) properties of the ( Bi,Pb )$_{2}$Sr$_{2}$Ca$_{2}$Cu$_{3}$0$_{y}$ superconductors. Samples with the nominal composition Bi$_{1.7}$Pb$_{0.3}$Sr$_{2}$Ca$_{2}$Cu$_{3}$Cs$_{x}$0$_{y}$ ( x = 0.0 - 1.0 ) were prepared by a solid state reaction in air as described in [l]. The crystal structures of the samples were characterized by x- ray analysis, SEM and microanalysis. The electrical resistivity was measured by the standard four -probe technique. The transport critical current density was determined from the current -voltage curves.
The x- ray measurements showed that all the samples consist of two superconducting phases 2223 and 22 12, with the 2223 phase predominance. The intensity of the ( 008 ), ( 00.10 ) and ( 00.12 ) reflections of the 2223 phase were more great than the intensity of others peaks of this phase, which suggest that the structure is textured in the [ 001 ] direction. SEM studies showed small -grained inclusions with predominant amount of Cs on the surface of samples. In the bulk of samples small -grained inclusions was not observed.
The obtained $\rho$(T) dependencies are of metal- type; for all samples only one superconducting transition caused by the 2 2 2 3 phase ( according to x -ray analysis ) was observed. It was found that additions of Cs lead to improving of superconducting properties (J$_{c}$ increases three times; T$_{c}$. on 1.3 -2.3 K; T$_{c,max}$ =108 K at x =0. 6 ).
The dependence of superconducting properties on composition and microstructure are discussed.
1. V. V. Petrashko et at., Superconductivity 1992, 5 (5), 893