Local and electronic structure of carbon and nitrogen atoms in oxycarbonitrate superconductors

Results of X-ray fluorescence measurements of new oxycarbonitrate supercond uctors MSr2Can-1CunOy (n = 1 or 2 and Al = Cu, C or NI) are presented. The experiments show that C atoms form a distorted CO3 oxyacid group with a par tial substitution of copper and nitrogen atoms in the Af sites. Based on th e comparison of nitrogen K alpha emission spectra and spectra of reference samples it is concluded that the CO32- group in (C,N)Sr2Can-1CunOy and (Cu, C,N)Sr2Can-1CunOy is substituted by the NO2- instead of the NO3- group. Thi s induces the creation of hole carriers in these compounds. (C) 2001 Elsevi er Science B.V. All rights reserved.