Structure, magnetic, and electrical properties of bismuth niobates doped with d-elements: XVII.1 Magnetic properties of Bi5Nb3–3xMn3xO15–δ solid solutions

Чежина, Н. В.; Королев, Д. А.; Fedorova, Anna; Жук, Н. А.; Филиппова, М. В.; Feltsinger, L. S.; Lutoev, V. P.; Макеев, Б. А.; Шевчук, С. С.; Nizovtsev, A. N.

doi:10.1134/s1070363217100012

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“…X-ray spectroscopy data shows that the amount of oxidized manganese(III) ions throughout the entire concentration range is greater in zinc preparations than in magnesium preparations. Earlier, we observed this interesting experimental fact while studying the magnetic behavior of solid solutions of heterovalent substitution Bi 5 Nb 3−3x Mn 3x O 15−δ and Bi 2 BaNb 2−2x Mn 2x O 9−δ [35,36]. It has been shown that with an increase in manganese dopant ions, the proportion of oxidized manganese ions increases in order to neutralize the effect of heterovalent substitution and reduce the number of oxygen vacancies that destabilize the crystal structure.…”

Section: Resultsmentioning

confidence: 70%

XPS and NEXAFS Characterization of Mg/Zn and Mn Codoped Bismuth Tantalate Pyrochlores

Zhuk,

Makeev,

Koroleva

et al. 2024

Inorganics

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Two series of the bismuth tantalate pyrochlore samples, codoped with Mg,Mn and Zn,Mn, were synthesized via solid-phase reaction. It was established that the Bi2Mg(Zn)xMn1−xTa2O9.5−Δ (x = 0.3; 0.5; 0.7) samples contain the main phase of cubic pyrochlore (sp. gr. Fd-3m) and an admixture of triclinic BiTaO4 (sp. gr. P-1). In both sets, the amount of BiTaO4 is proportional to the amount of manganese doping, however, zinc-containing samples have a higher level of impurities than magnesium-containing ones. The unit cell parameter of the Zn,Mn codoped bismuth tantalate phase increases with an increasing content of zinc ions in the samples from 10.4895(5) (x = 0.3) to 10.5325(5) Å (x = 0.7). The unit cell parameter of Mg,Mn codoped bismuth tantalate pyrochlores increases uniformly with an increasing index x(Mg) from 10.4970(8) at x = 0.3 to 10.5248(8) Å at x = 0.7, according to the Vegard rule. The NEXAFS and XPS data showed that the ions were found to have oxidation states of Bi(+3), Ta(+5), Zn(+2) and Mg(+2). In the Ta 4f XPS spectrum of both series of samples, a low energy shift of the absorption band characteristic of tantalum ions with an effective charge of (+5-δ) was observed. The XPS spectra of Bi4f7/2 and Bi4f5/2 also show a shift of bands towards lower energies which is attributed to the presence of some low-charge ions of transition elements in the bismuth position. The NEXAFS spectroscopy data showed that manganese ions in both series of samples have predominantly 2+ and 3+ oxidation states. XPS data indicate that in zinc-containing preparations the proportion of oxidized manganese ions is higher than in magnesium-containing ones.

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Section: Resultsmentioning

confidence: 70%