LOCAL ELECTRONIC STRUCTURE OF DOPING ATOMS IN MA2Can-1CunO2n+3 HIGH-Tc SUPERCONDUCTORS WITH [M-12(n-1)n] TYPE STRUCTURES

Results of X-ray fluorescence measurements of MA(2)Ca(n-1)Cu(n)O(2n+3) Compounds with [M-12(n - 1)n] type structures, (C0.8N0.2Sr2CuO5.3, [Cu-0.25(C,N)(0.75)]Sr2CaCu2Oy, Cu0.5V0.5Sr2CaCu2O7.5, Cu0.5V0.5Sr2Ca2Cu3O9.4, Cu0.5V0.5Sr2(Ca3.6Sr0.4)Cu5O13.5 and Cu0.5V0.5Sr2(Ca4.7Sr0.3)Cu6O15.3), are presented. The experiments show that C-atoms form a distorted CO3 oxyacid group with a partial substitution of copper and nitrogen atoms in the M-sites. We conclude that the CO32- group in (C,N) Sr2Can-1CunOy and (Cu,C,N) Sr2Can-1CunOy is substituted by the NO2- which induces the creation of the hole carriers in these compounds. We have found that V-atoms in the given compounds form (VO4)(3-) tetrahedrons and have a pentavalent state.