Complex Susceptibilities of Sr-doped YBa2Cu3O7-d Synthesized by the Polymerized Complex Method

We measured complex susceptibilities of Sr-doped YBa₂Cu₃O_7-d superconductors, YBa_2-xSr_xCu₃O_7-d (x=0-1.0) and determined the onset temperature of the superconducting transition. The samples were synthesized by the modified polymerized complex method. With increasing x, the onset temperature decreased, although the depletion was not large as those for Sr-doped YBa₂Cu₄O_y. Measurements of the phonon Raman spectra have revealed that with increasing x the frequencies of the Ba, Cu(2) and apex oxygen O(4) vibrational modes along c-axis change. Besides, at about 570 cm^-1, a small growth of a peak was observed with increasing x, which may be caused by oxygen disorder in the CuO chains. But no appreciable changes in hole density were found from optical absorption spectra.