Raman studies of the high pressure effects in high T-c superconductors

The effect of a hydrostatic pressure (up to 6GPa) on the Raman spectra of Y Ba2Cu3Ox (x=6.5 and overdoped) single crystals is investigated in the tempe rature range 77-300 K in connection with all available data in the literatu re for the other oxygen concentrations. All five strong modes (4A(g) + 1B(1 g)) are examined for both oxygen doping and compared with previously publis hed results. From the systematic investigation of the phonon spectral chara cteristics with the application of pressure, the formation or disappearance of the phases is examined. The results provide a spectroscopic support for the changes induced by the hydrostatic pressure on the chain ordering and the corresponding phases.