Effective Charges of Atoms of HTSC La2 – xSrxCuO4 Ceramics Determined from the Analysis of the Parameters of the Nuclear Quadrupole Interaction

Resumo

Using the comparison method of the calculated (the model of point charges) and experimental (Mössbauer spectroscopy and the nuclear magnetic resonance) parameters of the nuclear quadrupole interaction, it is shown that the effective charges of all the atoms of the lattices of the superconducting La_2–xSr_xCuO₄ ceramics correspond to the standard degrees of their oxidation, except for atoms of the planar oxygen, the lowered charge of which is interpreted as the result of localization on them of the hole appearing when La³⁺ ions are substituted by Sr²⁺ ions.