The exchange interactions and the state of manganese atoms in the solid solutions in Bi3NbO7 of cubic and tetragonal modifications

Чежина, Н. В.; Жук, Н. А.; Королев, Д. А.

doi:10.1016/j.jssc.2015.10.026

Cited by 10 publications

(1 citation statement)

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“…The niobium atoms are arranged in distorted coordination octahedra [6,10], the niobium-oxygen octahedra are bound by oxygen vertices, forming chains or blocks [3,6,[10][11][12][13][14]. Previous studies of the magnetic properties of solid solutions of niobate of bismuth of cubic modification containing paramagnetic ions of 3d-elements [15][16][17] have shown that, due to the charge imbalance and highly distorted coordination polyhedron in the dilute solutions, the paramagnetic atoms were preferably in the oxidized state, e.g. Ni(III), Mn(III), Mn(IV).…”

Section: Introductionmentioning

confidence: 99%

Magnetic Properties, EPR and NEXAFS – Spectroscopy of Iron-Doped Bi₃NbO₇ Ceramics

Belyy¹,

Lutoev²,

Жук³

et al. 2018

J. Sib. Fed. Univ. Chem.

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The measurements of magnetic susceptibility, EPR and NEXAFS-spectroscopy study of the ironcontaining solid solutions of bismuth niobate Bi 3 NbO 7 has indicated that iron atoms are represented by monomeric Fe(III) and Fe(III)-O-Fe(III) exchange bound dimers with the ferromagnetic and antiferromagnetic types of exchange in the solid solutions of cubic modification. The exchange parameter and monomeric and dimeric cluster distribution in Bi 3 Nb 1-x Fe x O 7-δ depending on the content of the paramagnetic atoms were calculated according to the model of Heisenberg-Diracvan Vleck. The solid solutions as well as iron oxides FeO, Fe 2 O 3 and Fe 3 O 4 were studied by the NEXAFS spectroscopy in order to determine the degrees of oxidation of iron atoms. The analysis of the NEXAFS Fe2p-spectra of iron-containing solid solutions and iron oxides revealed that the studied Fe atoms were mainly in the +3 oxidation state. The EPR spectrum of the sample with minimum iron content contained a symmetric signal with g = 4.27 with a weak shoulder at g ~ 8. The samples of Bi 3 Nb 1-x Fe x O 7-δ solid solutions at 0.02 ≤ х ≤ 0.04 had a low-intensity broad band in the region of g ~ 2.28 of their spectra. The spectra of EPR of the solutions with x > 0.04 exhibited a broad, slightly asymmetric line centered around g ~ 2.0.

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