Coordination of heterovalent iron atoms in SrCo1-yFeyO3-z solid solutions

Mossbauer spectroscopy was used to study hyperfine interactions on Fe-57 nu clei of SrCo1-yFeyO3-z solid solutions (0.2 less than or equal to y less th an or equal to 0.8). The Fe-57 spectra measured in the paramagnetic tempera ture range look like a superposition of two quadrupole doublets whose param eters correspond to high-spin Fe4+ cations ((delta) = 0.1 mm/s; (Delta) = 0 .4 mm/s) in the anion surrounding with coordination number 5 (tetragonal py ramid) and to Fe3+ cations ((delta) = 0.3 mm/s; (Delta) = 0.4 mm/s) in the distorted octahedral environment. The relative number and pattern of distri bution of heterovalent cations (Co4+, Co3+, Fe4+, and Fe3+) in the B-sublat tice of perovskites were determined. The values of the electronic exchange constants in the solid solutions obtained through Mossbauer spectroscopy we re compared with those obtained from thermodynamic calculations. The oxygen penetration in perovskites was found to depend on their composition and st ructure.