Studies of the La_{1 + x}Ba_{2 - X}Cu₃O_z prepared from highly homogeneous precursors

Single phase materials of La_{1 + x}Ba_{2 - x}Cu₃O_z with x = 0.0, . . . ,0.98, were synthesized from highly homogeneous precursors, prepared by spray-drying or the polymerized complex method. These samples were characterized using X-ray diffraction (XRD), Raman spectroscopy and AC susceptibility measurements. The effects of composition, processing time, temperature and oxygen partial pressure, on the formation and decomposition of La_{1 + x}Ba_{2 - x}Cu₃O_z prepared by different methods, were investigated. We found that: T_c gradually decreased with the increase of La content; orthorhombic distortions appear at x < 0.25 and x > 0.7; and single phase stoichiometric La-123 ceramic samples, obtained at low oxygen partial pressure and quenched, decomposed into La-123ss (x = 0.2) and BaCuO₂ after annealing at a rather low temperature, below 500°C.