Mobility and short-range ordering of oxygen in ifRrmBain2Cuin3Oinrm6+x by anelastic relaxation and possible correlation with the 90 K and 60 K superconducting phases

The evolution of two anelastic relaxation processes in RBa2Cu3O6+x (R = Y, Eu) above room temperature has been investigated and discussed over the whole range of the O stoichiometry. The processes seem to be associated with the O jumps in the O-I and O-II domains, and could provide the tool for evaluating the fractions of the 90 and 60 K superconducting phases.