Electric field gradient tensor in positions of rare-earth metals in RBa2Cu3O7 lattices

The parameters of the electric field gradient tensor (EFG) created in rare-earth metal (REM) sites of RBa2Cu3O7 lattices (R = Nd, Sm, Gd, Dy, Y, Ho, Er, Tm) by crystal lattice ions have been determined by the method of emission Mössbauer spectroscopy on 67Ga(67Zn) and 155Eu(155Gd) isotopes. The EFG tensor has been calculated for REM sites in the approximation of the point charge model. It was shown that the agreement between the experimental and calculated parameters of the EFG tensor can be achieved if the holes are preferably localized in the chain oxygen sublattice.