Neutron Scattering Study of Sr Substitution for Ba in YBa2Cu3O7-y

Neutron diffraction and inelastic scattering were carried out on YBa2-xSrxCu3O7-y (x=0.5, 1.0, 1.25). It was confirmed that the substitution of Sr for Ba in YBa2Cu3O7-y increases the oxygen vacancies in the Cu O chain. Moreover, the substitution strengthens the coupling between the Ba O plane and the Cu O chain, and reduces the crystal stability. These are the possible causes of Tc depression for Sr substituted YBa2Cu3O7-y.