V. P. Lutoev

Structure, magnetic, and electric properties of bismuth niobates doped with d-elements: XI. Magnetic susceptibility of Bi3NbO7 of cubic and tetragonal modifications

Study of magnetic susceptibility and ESR spectra of two modifications of bismuth niobate Bi3NbO7, tetragonal and cubic, has shown that a significant difference in the diamagnetic susceptibilities is observed at a reversible phase transition, which is associated with the presence of tetravalent niobium atoms combined in aggregates in the tetragonal modification of the complex oxide.

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 Bi5Nb3–3xFe3xO15–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.

Structure, magnetic, and electrical properties of bismuth niobates doped with d-elements: XIV. Magnetic behavior of Bi2BaNb2–2x Fe2x O9–δ solid solutions

Magnetic susceptibility and ESR properties of iron-containing Bi2BaNb2–2xFe2xO9–δ solid solutions with layered perovskite-like structure have been studied. In the diluted solid solutions, iron atoms are combined into Fe(III) dimers and tetramers with antiferro- and ferromagnetic exchange types. The exchange parameters and the distribution of aggregates in the solid solutions have been calculated as functions of the paramagnetic atoms fractions.

Structure, magnetic, and electrical properties of bismuth niobates doped with d-elements: XVI. Magnetic properties of manganese-containing solid solutions of bismuth orthoniobate BiNiO4

Magnetic susceptibility and ESR properties of manganese-containing solid solutions of bismuth orthoniobate BiNb1–xMnxO4–δ have been studied. Mn(II), Mn(III), and Mn(IV) atoms as well as their dimers exhibiting antiferro- and ferromagnetic types of exchange have been found in the solid solutions. Parameters of the exchange interactions in the clusters and the distribution of monomers and dimers of manganese atoms in the solid solutions have been calculated as functions of the paramagnetic atom fraction.

Structure, magnetic, and electrical properties of bismuth niobates doped with d -elements: XVII. 1 Magnetic properties of Bi 5 Nb 3–3 x Mn 3 x O 15–δ solid solutions

A monoclinic distortion of tetragonal cell was found in the solid solutions with layered perovskite-like structure [Bi5Nb3–3xMn3xO15–δ (0.005 < х ≤ 0.06)]. In the ESR spectra absorption bands with g-factors ~4.3 and 2.1 assigned to Mn(II) and Mn(IV) atoms are recorded. The studies of magnetic susceptibility of the Bi5Nb3–3xMn3xO15–δ solid solutions revealed the formation of ferro- and antiferromagnetically bonded dimers of Mn(II), Mn(III), and Mn(IV) atoms. The exchange parameters in dimers and the distribution of paramagnetic manganese atoms in dependence to solid solution concentrations were calculated.

Structure, magnetic, and electrical properties of bismuth niobates doped with d -elements: XIII. State of iron atoms in the Bi 3 Nb 1– x Fe x O 7–δ solid solutions

From the data of magnetochemical study and ESR spectra of samples of the Bi3Nb1–xFexO7–δ (х ≤ 0.06) solid solutions iron atoms in the solid solutions of cubic modification of bismuth niobate were found to be located as Fe(III) monomers and exchange-bonded Fe(III)–O–Fe(III) dimers with anti- and ferromagnetic exchange types. The exchange parameters and the distribution of monomers and dimers over the solid solution were calculated as functions of the paramagnetic atom fraction.

Structure, magnetic, and electrical properties of bismuth niobates doped with d -elements: XVIII. Magnetic susceptibility and ESR spectra of Bi 2 BaNb 2–2 x Mn 2 x O 9–δ solid solutions with layered perovskite-like structure

On the basis of the data of ESR and magnetic susceptibility of Bi2BaNb2–2xMn2xO9–δ solid solutions with perovskite-like structure ferro- and aniferromagnetic bonded dimers, trimers, and tetramers of Mn(II), Mn(III), and Mn(IV) atoms in various valence states were found. The distribution of aggregates and exchange parameters in the clusters were calculated as a function of fraction x of manganese atoms in the solid solutions. In the ESR spectra of diluted solid solutions there are absorption bands with g-factors ~4.3 and 2.1 assigned to Mn(II) and Mn(IV) atoms.