From theESRexperimental results, a Modulated Structure with the twined Y-unit-cells in YBa2Cu3O7(YBCO) ceramics have been revealed, in which appear two types of the [Cu-Y-Cu] Electron Spin Superexchange Coupled Pairs. On the basis of the particular behaviour of the quasi-free electrons in close connection with this Modulated Structure, some fundamental problems of the Superconducting Nano-Micromechanism inYBCOhave been interpreted.
