Raman studies in off-stoichiometric superconducting compounds of the type Bi_2-xPb_ySr₂Ca₂Cu₃O_δ

Raman measurements performed on superconducting ceramic samples of the type Bi_2-xPb_ySr₂Ca₂Cu₃, with y=0.3, 0.6, 0.9 and x=0.1, 0.2, are reported. All Raman phonons with symmetry A_1g have been observed. Phonon identification has been carried out using previous reported studies of the Bi₂Sr₂Ca_n-1Cu_nO_{2 n+y} system, for n=1, 2, 3. A description of the detected Raman active modes in all samples is given, and the study of these modes in terms of the relative amount of lead-to-bismuth content and thermal treatment is also presented.