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The temperature and oscillation frequency dependences of internal friction and shear modulus of superconducting YBa2Cu3O7- delta specimens are measured using a multifunction internal-friction torsion pendulum to study the degree of ordering and the migration of oxygen deficiency sites in the superconductor YBa2Cu3O7- delta . It is found that relaxation is most likely to occur in units where one oxygen site is surrounded by four barium ions rather than along the O-Cu-O chain. This indicates that an internal-friction study provides a powerful way of investigating the relaxation process of oxygen atoms as well as the degree of ordering of oxygen deficiencies in relation to superconductivity features.

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