Site-Dependent 18O Substitution in YBa2Cu3O7 Studied by Raman Scattering Measurements

Abstract
The site-dependent replacement of 16O with 18O in YBa2Cu3 16O7 has been identified by Raman scattering measurements of different vibrational modes in the CuO2 and BaO planes. The Raman shifts due to isotope substitution for different modes in inequivalent oxygen positions show different temperature dependences. The activation energy of oxygen replacement in the BaO plane is lower than that in the CuO2 plane. The results show that the degree of oxygen substitution is site-dependent.