N. V. Chezhina

Structure, magnetic, and electrical properties of bismuth niobates doped with d-elements: XII. Magnetic behavior of Bi3Nb1–xMnxO7–δ solid solutions

Magnetic behavior of Bi3Nb1–xMnxO7–δ solid solutions of cubic and tetragonal modifications has been examined in comparison. The magnetic susceptibility studies have revealed that paramagnetic manganese atoms in the solid solutions of cubic and tetragonal modification exist as Mn(III) and Mn(IV) monomers as well as exchange-bound dimers: Mn(III)OMn(III), Mn(IV)OMn(IV), and Mn(III)OMn(IV). The exchange parameters and the distribution of monomers and dimers in the solid solutions have been determined as function of the paramagnetic atoms fraction.

Structural, magnetic, and electric properties of bismuth niobates doped with d elements: X. State of nickel in Bi3Nb1-xNixO7-δ solid solutions with a fluorite-type structure

A magnetic susceptibility study of Bi3Nb1-xNixO7-δ solid solutions showed that paramagnetic nickel atoms occur in the solid solutions as Ni(II) monomers, Ni(III) monomers, and exchange-coupled dimers formed by Ni(III) atoms and characterized by the magnetic exchange parameter J of −155 cm−1. The distribution of the monomers and dimers of nickel atoms as a function of the solid solution concentration was calculated.

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.

Atom states and interatomic interactions in perovskite-like oxides: XXXV. Magnetic properties of solid solutions of lanthanum manganites doped with ytterbium and calcium in LaAlO3

The solid solutions La1–YYbyAlO3 (y = 0.01–0.20) and La1–0.397xYb0.067xCa0.33xMnxAl1–xO3 (x = 0.01–0.10) were studied by magnetic dilution method. The state of paramagnetic elements and the character of exchange interactions between them were determined on the basis of examination of magnetic properties. Clustering of manganese atoms in the La1–0.397xYb0.067xCa0.33xMnxAl1–xO3 solid solution, as distinct from the La1–0.67xCa0.33xMnxAl1–xO3 solid solutions studied before, is determined by the presence of ytterbium atoms in the perovskite structure of the complex oxides under study.

State of atoms and interatomic interactions in perovskite-like oxides: XXXIV. State of europium atoms and exchange interactions in La1–yEuyAlO3

A series of solid solutions of the La1–yEuyAlO3 composition was studied by the method of magnetic dilution in the concentration range 1–20 mol % of europium atoms. Europium atoms in the solid solutions were found to take part in the antiferromagnetic superexchange interactions. Magnetic characteristics at the infinite dilution are described as existence of single Eu(III) atoms with a large contribution of Van Vleck’s temperature independent paramagnetism (∼0.001 emu/mol).

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.

State of atoms and interatomic interactions in complex perovskite-like oxides: XXXVI. Magnetic susceptibility of LaFexGa1–xO3 and La1–0.2xSr0.2xFexMg0.2xGa1–1.2xO3 solid solutions

Magnetic susceptibility of solid solutions based on lanthanum gallate doped with iron, and also with iron, strontium, and magnesium in the ratio 5 : 1 : 1 was studied. In both systems at the infinite dilution clusters of iron atoms remain, the fraction of these clusters in lanthanum gallate doped only with iron comprising 0.4 of the total fraction of clusters in the gallate doped with strontium and magnesium.