Soft X-Ray Absorption Spectroscopy as a Method to Study Y 1– y Ca y BaCo 4– x M x O 7 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 CaBaCo 4 O 7 , Y 0.5 Ca 0.5 BaCo 4 O 7 , Y 0.5 Ca 0.5 BaCo 4– x Fe x O 7 , and Y 0.5 Ca 0.5 BaCo 4–z Zn z O 7 . 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 Со L 3 /Ba M 5 spectra, and the relative contents of both Fe and Zn doping elements and Co 2+ and Co 3+ ions have been determined. It has been found that the substitution of iron ions for some cobalt ions (cobaltite Y 0.5 Ca 0.5 BaCo 4– x Fe x O 7 ) transforms some Co 3+ ions to Co 2+ 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 Y 0.5 Ca 0.5 BaCo 4– z Zn z O 7 ) increases the concentration of high-spin Co3+ ions. The tetrahedral coordination of the Co 2+ and Co 3+ ions has been confirmed.