Paramagnetic Centers Created Under Mechanochemical Treatment of Mixed Molybdenum-Vanadium Oxides

Колбанев, И. В.; Degtyarev, E. N.; Стрелецкий, А. Н.; Кокорин, А. И.

doi:10.1007/s00723-016-0778-4

Cited by 11 publications

(5 citation statements)

References 27 publications

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“…Spectrum b in Figure is the asymmetric single line with parameters g ≈ 1.980, Δ B pp ≈ 23.7 mT, which are very close to those of the initial V 2 O 5 sample (see above). Such spectrum b is typical for the aggregated VO 2+ PCs at V 2 O 5 surface observed and discussed previously. ,, We should note that this singlet characterizes some areas of aggregated VO 2+ PCs with very high local concentration of PCs with strong electron spin exchange coupling between them.…”

Section: Resultssupporting

confidence: 68%

“…EPR spectra at 77 K of V 2 O 5 oxide initial and mechanically treated in Aronov mill during 3 and 12 min are shown in Figure . Initial spectrum is typical for V 2 O 5 oxide whose contents have a certain amount of V 4+ paramagnetic centers (PCs) as described already in refs and . One can see a complex spectrum with a superposition of a broad single line (its peak-to-peak line width Δ B pp ≈ 21.0 mT, and g ≈ 1.973) with much less intensive lines of the well-resolved multiplet V 4+ spectrum (Figure a).…”

Section: Resultsmentioning

confidence: 71%

“…Such spectrum b is typical for the aggregated VO 2+ PCs at V 2 O 5 surface observed and discussed previously. 20,21,43 We should note that this singlet characterizes some areas of aggregated VO 2+ PCs with very high local concentration of PCs with strong electron spin exchange coupling between them.…”

Section: ■ Experimental Sectionmentioning

confidence: 96%

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Influence of Aluminum Addition on the Structure and Feathers of V₂O₅ Oxide Prepared by Mechanochemical Activation

et al. 2019

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The defect structure of the samples formed under mechanochemical activation (MCA) of V2O5 and mixed Al/V2O5 oxides has been analyzed. Al/V2O5 mixture is one of the most perspective thermites, and using the MCA, one can considerably increase the rate of its combustion, for example, by creating high concentration of the defects. To our knowledge, this scientifically interesting and probably applicable system has not been investigated in detail. Samples were characterized by X-ray diffraction, scanning electron microscopy, BET measurements, and X-band electron paramagnetic resonance spectroscopy. MCA of V2O5 at the split-stage was accompanied by forming the nanosized (∼80 nm) particles which contained various defects: boundaries of coherent scattering areas, microstrains, and paramagnetic centers (PCs) of two types. The first type of PCs contains the isolated defects (V4+ ions) located on the surface of nanoparticles, and the second type of PCs is a kind of clusters formed by V4+ PCs with a very high local concentration of defects. Increasing of the milling time results in dominance of friction processes accompanied by the increase of particle sizes and decreasing the specific surface area but, at the same time, the increase of grain surfaces, sizes of microstrains, and the PCs concentration. The aluminum addition stimulates aggregation processes of particles into composites, but the high concentration of different defects is preserved. We assume that our results concerning the Al/V2O5 system will be a serious supplement to the investigation of thermites prepared as a mixture of aluminum with different metal oxides.

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Section: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 71%

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Influence of Aluminum Addition on the Structure and Feathers of V₂O₅ Oxide Prepared by Mechanochemical Activation

et al. 2019

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“…The EPR spectrum of the nanocomposite TiO 2 /MoO 3 :V 2 O 5 with the molar ratio 5:0.5:0.5, shown in Figure , differs considerably from those presented in Figure . The initial signal a recorded in the dark conditions is typical for paramagnetic V 4+ or OV 2+ centers described in many publications (refs , , and refs therein). These centers exhibit a pronounced tendency to form aggregates.…”

Section: Results and Discussionmentioning

confidence: 97%

Determination of the Energy Levels of Paramagnetic Centers in the Band Gap of Nanostructured Oxide Semiconductors Using EPR Spectroscopy

et al. 2018

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A detailed analysis of the nature and photoinduced reactions of paramagnetic centers (PCs) in TiO 2 based semiconductor nanoparticles has been performed, and energy diagrams of the investigated samples with the energy level positions in the band gap are determined using electron paramagnetic resonance (EPR) technique under illumination in situ. This study gives a new method for constructing the zone diagram of nanostructured semiconductors. N • , Ti 3+ , and Mo 5+ PCs were detected in TiO 2 /MoO 3 samples, and Ti 3+ and V 4+ centers were observed in the TiO 2 /MoO 3 :V 2 O 5 one. The determined energy position of PCs in the band gap of nanostructured semiconductors are located from the valence band on 2.9 eV for Ti 3+ ions, 2.7 eV for Mo 5+ ions, 2.2 eV for V 4+ PCs, and 1.4 eV below the bottom of the conduction band for N • radicals. The effect of illumination is reversible during a long time: approximately 24 h because of a separation of the photogenerated charge carriers just after excitation between different semiconductor oxide nanosized particles connected by nanoheterojunctions. These results can be useful for understanding the mechanism of photocatalytic reactions and further practical applications of the nanoheterojunction materials such as TiO 2 /MoO 3 and TiO 2 /MoO 3 :V 2 O 5 oxides.

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“…As a result of surface valence measurement by XPS, Sn was Sn 2+ :Sn 4+ = 42.3:57.7, and Mo was Mo 4+ :Mo 5+ :Mo 6+ = 1.6:5.5:92.9. One plausible reason for the difference in the valence of elements between the crystal structure and the surface is the formation of dangling bonds 26) because of the planetary ball milling, and subsequent surface reconstruction. It is conceivable that the proportion of Mo(VI) increased as a result of reoxidation of Mo because of the exposure to ambient air after milling.…”

Section: Resultsmentioning

confidence: 99%

Antiviral and antifungal activities of tin molybdenum solid solution oxide prepared using mechanochemical processing

Sakai,

Sunada,

Mochizuki

et al. 2023

J. Ceram. Soc. Japan

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Using SnO and MoO 3 as starting materials, a SnO 2 MoO 2 solid solution (SnMO) was prepared using mechanochemical method. Then its antiviral and antifungal activities were evaluated. The obtained sample was a powder with specific surface area of 5.7 m 2 /g with a rutile-type crystal structure. The amount of ion elution for SnMO into 1/500NB solution was an order of magnitude lower than that of MoO 3 . This powder exhibited high antiviral activity against both bacteriophage Q¢ and bacteriophage ¯6, suggesting contributions to antiviral activity by both low pH and eluted ions from the powder. Furthermore, a test based on JIS standards revealed that SnMO possesses high antifungal activity. These findings indicate SnMO as an effective material against widely various microorganisms.

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Paramagnetic Centers Created Under Mechanochemical Treatment of Mixed Molybdenum-Vanadium Oxides

Cited by 11 publications

References 27 publications

Influence of Aluminum Addition on the Structure and Feathers of V₂O₅ Oxide Prepared by Mechanochemical Activation

Influence of Aluminum Addition on the Structure and Feathers of V₂O₅ Oxide Prepared by Mechanochemical Activation

Determination of the Energy Levels of Paramagnetic Centers in the Band Gap of Nanostructured Oxide Semiconductors Using EPR Spectroscopy

Antiviral and antifungal activities of tin molybdenum solid solution oxide prepared using mechanochemical processing

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Paramagnetic Centers Created Under Mechanochemical Treatment of Mixed Molybdenum-Vanadium Oxides

Cited by 11 publications

References 27 publications

Influence of Aluminum Addition on the Structure and Feathers of V2O5 Oxide Prepared by Mechanochemical Activation

Influence of Aluminum Addition on the Structure and Feathers of V2O5 Oxide Prepared by Mechanochemical Activation

Determination of the Energy Levels of Paramagnetic Centers in the Band Gap of Nanostructured Oxide Semiconductors Using EPR Spectroscopy

Antiviral and antifungal activities of tin molybdenum solid solution oxide prepared using mechanochemical processing

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Influence of Aluminum Addition on the Structure and Feathers of V₂O₅ Oxide Prepared by Mechanochemical Activation

Influence of Aluminum Addition on the Structure and Feathers of V₂O₅ Oxide Prepared by Mechanochemical Activation