HIGH-TEMPERATURE BISMUTH CUPRATE SUPERCON DUCTORS SYNTHESIS AND CHARACTERIZATION

High temperature superconductor phases synthesis by coprecipitation in alkaline solution is reported. (Bi1,6Pb0,4)Sr2Ca1Cu2O8+x and (Bi1,6Pb 0,4)Sr2Ca2Cu3O10+y noted (2212) and (2223) have been prepared and stud ied. From aqueous nitrate solutions of Bi, Pb, Sr, Ca and Cu and oxali c acid aqueous solution as well as ethylene glycol, using an organic b ase (the triethylamine), the pH was increased up to the path of the pr ecipitation zone (pH = 10.5-11.2). This method assures a good granulom etric homogenity of powders. Thermal analysis and characterization of the different components produced during the synthesis have been studi ed by DTA (differential thermal analysis)-TGA (thermogravimetric analy sis), X-ray diffraction at different temperature and by Infrared spect roscopy with a Fourier transformation . The measurements of magnetic s usceptibility for the 2212 (with and without lead) and 2223 (with lead ) phases have permitted us to observe the critical temperatures of 84 K, 87 K and 114 K.