Raman Scattering in MBa2Cu3O7 with M=Y, Eu, and Gd=Effect of O18 Substitution and Oxygen Vacancies On the Cu-O Vibrational Modes
We have studied the Cu-O vibrations in the MBa2Cu3O7 systems with M=Y,Eu,andGd by Raman spectroscopy. The observed Raman features are similar in the three systems. The four Raman bands in the 300-700 cm-1 frequency region exhibit isotopic shifts upon O18 substitution implying that these modes involve oxygen vibrations. In oxygen-deficient YBa2Cu3O7- samples prepared in the range 0< <0.7 within the orthorhombic structure, the A1g axial stretch mode is found to undergo both a softening and broadening with increasing oxygen deficiency. Furthermore, the Raman feature in the 550-600 cm-1 region shows an increase in intensity. The latter is attributed to disorder activation of the Cu-O chain mode, normally forbidden in the stoichiometric compound. These features and the emergence of a distinct Raman peak near 390 cm-1 in oxygen-deficient samples suggest that Raman spectroscopy could be used for characterizing oxygen stoichiometry of high-Tc superconductors.
Montclair State University Digital Commons Citation
Kourouklis, G. A.; Jayaraman, Aiyasami; Batlogg, Bertram; Cava, Robert J.; Stavola, Michael; Krol, Denise M.; Rietman, Edward A.; and Schneemeyer, Lynn, "Raman Scattering in MBa2Cu3O7 with M=Y, Eu, and Gd=Effect of O18 Substitution and Oxygen Vacancies On the Cu-O Vibrational Modes" (1987). Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works. 475.