Structure, magnetic, and electrical properties of bismuth niobates doped with d -elements: XV. Exchange interactions and state of iron atoms in the Bi 5 Nb 3–3 x Fe 3 x O 15–δ solid solutions

Magnetic susceptibility of Bi5Nb3–3x Fe3x O15–δ (х ≤ 0.06) iron-containing solid solutions with perovskite-like structure was studied. Exchange-bound aggregates of Fe(III) atoms with antiferro- and ferromagnetic exchange types are formed in the solid solutions. The exchange parameters in the clusters and the distribution of tetramers and dimers of Fe(III) atoms over the solid solutions as functions of paramagnetic atom content were calculated.