OPTICAL REFLECTIVITY OF SUPERCONDUCTING BI3.9PB0.1SR3CA3CU4OX OBTAINED BY GLASS-CERAMIC ROUTE IN 0.6-6.2 EV RANGE

The room temperature reflectance spectra in the UV-VIS-NIR region (0.6 -6.2 eV) for the superconducting ceramic phase of Bi3.9Pb0.1 Sr3Ca3Cu4 Ox, Obtained by glass-ceramic route have been studied by Kramers-Kroni g (KK) analysis. From these analyses, the real (epsilon') and imaginar y (epsilon '') parts of the complex dielectric function, epsilon = eps ilon' + i epsilon '', optical conductivity (sigma') and the absorption spectra (alpha) have been determined. These studies have indicated th e presence of plasmon around 1 eV and have also shown that in these ox ide systems, Bi-O and Sr-O layers have little role to play in the mech anism of superconductivity. The possibility of excitonic absorption in Bi-based high T-c superconductors has also been discussed from the kn owledge of the absorption spectra.