RAMAN MICROSCOPY EXAMINATION OF PHASE EVOLUTION IN BI(PB)-SR-CA-CU-O SUPERCONDUCTING CERAMICS

Raman microspectroscopy (RMS) and imaging Raman microscopy (IRM) were used to probe the composition and spatial distribution of chemical pha ses in Bi(Pb)-Sr-Ca-Cu-O (BSCCO) ceramic superconductor powders and si lver-BSCCO composites. The Raman techniques were used to identify vari ous phases, including alkaline earth cuprates, CuO, Bi-2212, Bi-2223, and Pb-containing phases. Changes in the Ca/Sr ratios in (Ca, Sr)(2)Cu O3 phases were distinguished by differences in orientation with respec t to polarization of the exciting radiation. Variations were observed in the content and distribution of lead in various phases formed durin g intermediate stages of the thermal processing of composite conductor s. The spatial distribution of the various phases detected in powder a nd composite conductors was established to a resolution of a few micro ns by collecting images of the Raman scattering at wavelengths corresp onding to the signature peaks of the observed phases. Reference Raman spectra of the major phases observed in the BSCCO system are also repo rted. The Raman techniques, when combined with complementary technique s, such as x-ray diffraction and electron microscopy, can provide valu able information about the reaction paths and mechanisms of the high t emperature BSCCO superconducting ceramics.