Soft X-Ray Absorption Spectroscopy as a Method to Study Y1-y Ca y BaCo4-x M x O7 Cobaltites (M = Fe, Zn)

Soft X-ray absorption spectroscopy has been used to determine the charge state and content of cobalt ions in doped cobaltites CaBaCo4O7, Y0.5Ca0.5BaCo4O7, Y0.5Ca0.5BaCo4-x Fe (x) O-7, and Y0.5Ca0.5BaCo4-zZnzO7. A method has been proposed to determine the relative concentrations of cobalt ions in barium-containing cobaltites from the relative intensities of X-ray absorption D<inverted exclamation>D 3/4 L (3)/Ba M (5) spectra, and the relative contents of both Fe and Zn doping elements and Co2+ and Co3+ ions have been determined. It has been found that the substitution of iron ions for some cobalt ions (cobaltite Y0.5Ca0.5BaCo4-x Fe (x) O-7) transforms some Co3+ ions to Co2+ ions. It has been found that iron ions are in the 3+ charge state and have tetrahedral coordination with oxygen ions. The substitution of divalent zinc ions for some cobalt ions (cobaltite Y0.5Ca0.5BaCo4-z Zn (z) O-7) increases the concentration of high-spin Co3+ ions. The tetrahedral coordination of the Co2+ and Co3+ ions has been confirmed.