Studies of the La1+xBa2-xCu3Oz prepared from highly homogeneous precursors

Single phase materials of La1+xBa2-xCu3Oz 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 lime, temperature and oxygen partial pressure, on the formation and decomposition of La1+xBa2-xCu3Oz, 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 degrees C. (C) 1998 Elsevier Science Ltd. All rights reserved.