PHYSICAL CHARACTERIZATION AND VIBRATIONAL SPECTROSCOPY OF BI(PB) CUPRATE 2212 CERAMICS PREPARED BY SOL-GEL

Samples of bismuth cuprate with and without lead substitution were prepared by the sol-gel method. The general formula was Bi2-xPbxSr2CaCu2O8+delta, where 0 less-than-or-equal-to x less-than-or-equal-to 0.6. The samples were characterized by X-ray diffraction (XRD), electron probe microanalysis (EPMA), magnetic susceptibility, Raman spectroscopy and IR reflectance. Regarding homogeneity, density, purity and superconductivity, optimal behavior was found x = 0.2-0.4. An increase of hole concentration in the CUO2-planes with Pb2+/Bi3+ ratio was observed from the optical data. The Raman spectra modifications with lead substitution are discussed. Evidence of the interaction between CuO2-Plane hole continuum and 150 cm-1 IR active modes was found.