Antiferromagnetism induced by oxygen vacancies in V<sub>2</sub>O<sub>5</sub>polycrystals synthesized by the Pechini method

Dreifus, Driele von; Godoy, Marcio Peron Franco de; Rabelo, Adriano C.; Rodrigues, Ariano De Giovanni; Gobato, Y. Galvão; Camargo, P.C. de; Pereira, Ernesto C.; Oliveira, A. J. A. de

doi:10.1088/0022-3727/48/44/445002

Cited by 13 publications

(7 citation statements)

References 53 publications

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“…The fundamental absorption in crystalline V 2 O 5 is mostly due to the change from oxygen p-type to a vanadium 3d-type wave-function [61]. The current study confirms that the band gap value of V 2 O 5 is 2.26 eV due to indirect optical transitions, as previously reported which recorded the band gap of V 2 O 5 in the range of 2.15-2.65 eV [62].…”

Section: Discussionsupporting

confidence: 91%

Structural control of V2O5 nanoparticles via a thermal decomposition method for prospective photocatalytic applications

Ashery

Elnouby

El-Maghraby

et al. 2023

Beni-Suef Univ J Basic Appl Sci

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Background Recently, transition-metal oxides have represented an exciting research topic, especially their fundamental and technological aspects. Here, vanadium pentoxide nanoparticles (V2O5-NPs) were synthesized through the thermal decomposition of ammonium meta-vanadate. In the current study, we investigated the photocatalytic activity of V2O5-NPs to develop and regulate the V2O5 structure for adsorption applications. Results The obtained nanoparticles were inspected by X-ray diffraction, scanning electron microscope, transmission electron microscope, and differential thermogravimetric analysis, which proved the formation of the nanorod structure. The ultraviolet–visible absorption spectra revealed a 2.26 eV band gap for V2O5-NPs that correlates with indirect optical transitions. The photocatalytic activity of the V2O5-NPs was investigated by methylene blue (MB) degradation in aqueous solutions. An initial concentration of 25 ppm, a temperature of 40 °C, 40 mg of adsorbent mass, and 1 h of contact time were the optimal conditions for the efficient removal of MB that could reach up to 92.4%. The mechanism of MB photocatalytic degradation by V2O5-NPs is explained. Conclusions The photodegradation data better fit with the Langmuir isotherm model. The thermodynamic parameters indicated that the adsorption was spontaneous and endothermic. The reaction kinetics followed the pseudo-second-order model. Thermally prepared V2O5-NPs offer a simple and efficient approach for selective MB removal from an aqueous medium. Graphical abstract

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Section: Discussionsupporting

confidence: 91%

Structural control of V2O5 nanoparticles via a thermal decomposition method for prospective photocatalytic applications

Ashery

Elnouby

El-Maghraby

et al. 2023

Beni-Suef Univ J Basic Appl Sci

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“…Although V 2 O 5 is diamagnetic in nature, the experimental magnetic measurements conducted on the oxygen deficient compositions showed a large variation in the observations ranging from ferromagnetism [27,29,32], antiferromagnetism [51] to mixture of both [28,30].…”

Section: Discussionmentioning

confidence: 99%

Polaronic Correlations in Magnetic Behavior of Oxygen Deficient V2O5

Sarkar¹,

Biswas²,

Kakkar³

et al. 2021

Preprint

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In this paper, we investigate the magnetic behaviour of oxygen deficient vanadium pentoxide and its correlation with DC electrical transport. The undoped V 2 O 5 sample is synthesized by thermal decomposition resulting in oxygen deficient polycrystalline nature. It has a crystallite size of about 80 nm and a chemical stoichiometry of V 2 O 4.65 with a significant V 4+ states in addition to V 5+ as seen from X-ray diffraction and X-ray photoelectron spectroscopy respectively. The optical studies reveal a bandgap of 2.2 eV and a significant emission due to defects (1.8 eV) as well as Moss-Burstein effect(3.1 eV) which arises due to gap states and split in conduction band respectively. The temperature dependant electrical conductivity and thermopower measurements clearly demonstrate a polaronic conduction mechanism of small polaron hopping with hopping energy of 0.112 eV. The V 2 O 5 sample is found to show a strong field as well as temperature dependent magnetic behaviour when measured using sensitive SQUID magnetometer. It shows a positive magnetic susceptibility at all temperatures (5-300 K) at low field (µ 0 H= 0.1 T). The observed behavior is found to be a mix of ferromagnetism (FM) and antiferromagnetism (AFM, θ = −2.1 K in CW fit). On the other hand, for high field (µ 0 H= 1 T), it showed FM only at low temperatures and abruptly becomes diamagnetic at 31.2 K. This varied magnetic behavior has been attributed to small polaron hopping which arises because of oxygen vacancy defects compensated by charge defects of V 4+ and transition from bound to free polarons seen from transport. This is further revealed as strong hybridization of V bonded to oxygen vacancy V O and neighboring V 5+ ions, resulting in net magnetic moment per vacancy (3.959 µ B ) as predicted from first principle calculations. The insignificantly low energy difference between FM and AFM interactions observed from calculations and their critical dependence on oxygen vacancy concentrations justify the varied magnetic behaviour of V 2 O 5 reported in the literature.

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“…7(a and c). It was observed the paramagnetic behavior at 5 K for composites 27 1 and 3 in Fig. 7(a and c) was not completely be saturated up to 6 T. This may be due to the surface spin canting that is related to the volume of particles.…”

Section: Magnetic Properties Of the Nanocompositesmentioning

confidence: 90%

Preparation of TiO₂/VO_x, TiO₂/SiO₂, and VO_x/SiO₂ nanostructures by hydrothermal methods and determination of their magnetic properties

Tammim

Kaya

et al. 2023

New J. Chem.

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Antiferromagnetism induced by oxygen vacancies in V₂O₅polycrystals synthesized by the Pechini method

Cited by 13 publications

References 53 publications

Structural control of V2O5 nanoparticles via a thermal decomposition method for prospective photocatalytic applications

Structural control of V2O5 nanoparticles via a thermal decomposition method for prospective photocatalytic applications

Polaronic Correlations in Magnetic Behavior of Oxygen Deficient V2O5

Preparation of TiO₂/VO_x, TiO₂/SiO₂, and VO_x/SiO₂ nanostructures by hydrothermal methods and determination of their magnetic properties

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Antiferromagnetism induced by oxygen vacancies in V2O5polycrystals synthesized by the Pechini method

Cited by 13 publications

References 53 publications

Structural control of V2O5 nanoparticles via a thermal decomposition method for prospective photocatalytic applications

Structural control of V2O5 nanoparticles via a thermal decomposition method for prospective photocatalytic applications

Polaronic Correlations in Magnetic Behavior of Oxygen Deficient V2O5

Preparation of TiO2/VOx, TiO2/SiO2, and VOx/SiO2 nanostructures by hydrothermal methods and determination of their magnetic properties

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Antiferromagnetism induced by oxygen vacancies in V₂O₅polycrystals synthesized by the Pechini method

Preparation of TiO₂/VO_x, TiO₂/SiO₂, and VO_x/SiO₂ nanostructures by hydrothermal methods and determination of their magnetic properties