Mössbauer study of the HgBa2Can−1CunO2n+2 ceramics

The parameters of the electric-field gradient tensor at the copper, barium, and mercury sites in the HgBa2Can−1CunO2n+2 lattices (n=1,2,3) have been determined by Mössbauer emission spectroscopy on the 67Cu(67Zn), 133Ba(133Cs), and 197Hg(197Au) isotopes, and calculated in the point-charge approximation. An analysis of these results combined with available 63Cu NMR data showed that the experimental and theoretical data can be reconciled by assuming that the holes originating from defects in the material are localized primarily on the sublattice of the oxygen lying in the copper plane [for HgBa2Ca2Cu3O8, in the plane of the Cu(2) atoms].