D. A. Korolev

Atom state and interatomic interactions in complex perovskite-like oxides: XXIX. Influence of strontium concentration on special features of magnetic dilution in the La(Sr)CrO3-LaGaO3 system

Fractions of clusters and single chromium atoms were calculated for the series of solid solutions with various strontium content within the framework of diluted solution model using Heizenberg-Dirack-van-Vleck theory. A substantial influence of strontium concentration on the quantity of various clusters was found. For the systems with greater strontium contents the deviations from Curie-Weiss law are observed, which point to the presence of a noncompensated magnetic moment.

Atom states and interatomic interactions in perovskite-like oxides: XXVII. Influence of strontium concentration on interatomic interactions and conductivity in lanthanum gallates doped with strontium and chromium

Solid solutions based on lanthanum gallate and containing chromium and strontium in the ratio 2:1 as doping elements were studied by the method of static magnetic susceptibility, electron paramagnetic resonance spectroscopy, and impedance spectroscopy. Clustering of chromium atoms resulting in the formation of large aggregates of paramagnetic atoms is strengthened as the amount of strontium in the system increases.

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.

State of atoms and interatomic interactions in complex perovskite-like oxides: XXX. Influence of the nature of diamagnetic substituents on the dynamics of clustering in lanthanum gallate doped with strontium, chromium, and magnesium

The fractions of clusters and single chromium atoms were calculated by the diluted solution and Heisenberg-Dirac-van-Vleck models for a series of solid solutions containing chromium, strontium, and magnesium in the ratio 5:1:1, respectively. A principal genetic relationship was revealed between La1−0.2xSr0.2x·CrxGa1−xO3−δ, La1−0.5xSr0.5xCrxGa1−xO3−δ, and La1−0.2xSr0.2xCrxGa1−1.2xMg0.2xO3−δ systems. Deviations from Curie-Weiss law are observed for the systems with the ratio [Cr]:[Sr]:[Mg]=5:1:1, which point to a noncompensated magnetic moment.

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.

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.