Vanadium Spinel Research Articles

Analysis of magnesia-carbon bricks erosion in vanadium extraction converters: Insights from dynamic experiments and interface characterization

This paper uses a rotary furnace to simulate the dynamic erosion behavior of various magnesia-carbon bricks within a vanadium extraction converter, focusing on the effects of carbon content and antioxidants on erosion. The results indicate that vanadium-rich slag primarily consists of oxide solid solutions, iron vanadium spinel, and metallic Fe. Adding aluminum and silicon powders to the bricks reduces apparent porosity, increases body density, and improves slag erosion resistance. However, an increase in carbon content (12.54 wt% to 18.59 wt%) within magnesia-carbon bricks correlates with decreased high-temperature strength, exacerbating the reaction propensity with slag and consequent structural damage. Analysis of the interface phase between magnesia-carbon bricks and vanadium slag reveals a predominance of metal phase, spinel phase, and liquid slag phase. Thermodynamic calculations suggest an initial reaction between MgO and C on the brick surface, yielding Mg vapor and CO gas, while C reacts with slag to produce Cr and V elements, leading to surface structure degradation. Subsequent slag encasement and dissolution of remaining MgO via decarburization channels further erode magnesia-carbon bricks. Cumulative erosion iterations ultimately culmi nate in performance failure of magnesia-carbon bricks.

Genotoxicity and heating Performance of VxFe3-xO4 nanoparticles in Health applications

The applications of magnetic nanoparticles (MNPs) as biocatalysts in different biomedical areas have been evolved very recently. One of the main challenges in this field is to design affective MNPs surfaces with catalytically active atomic centres, while producing minimal toxicological side effects on the hosting cell or tissues. MNPs of vanadium spinel ferrite (VFe2O4) are a promising material for mimicking the action of natural enzymes in degrading harmful substrates due to the presence of active V5+ centres. However, the toxicity of this material has not been yet studied in detail enough to grant biomedical safety. In this work, we have extensively measured the structural, compositional, and magnetic properties of a series of VxFe3-xO4 spinel ferrite MNPs to assess the surface composition and oxidation state of V atoms, and also performed systematic and extensive in vitro cytotoxicity and genotoxicity testing required to assess their safety in potential clinical applications. We could establish the presence of V5+ at the particle surface even in water-based colloidal samples at pH 7, as well as different amounts of V2+ and V3+ substitution at the A and B sites of the spinel structure. All samples showed large heating efficiency with Specific Loss Power values up to 400 W/g (H0 = 30 kA/m; f = 700 kHz). Samples analysed for safety in human hepatocellular carcinoma (HepG2) cell line with up to 24h of exposure showed that these MNPs did not induce major genomic abnormalities such as micronuclei, nuclear buds, or nucleoplasmic bridges (MNIs, NBUDs, and NPBs), nor did they cause DNA double-strand breaks (DSBs) or aneugenic effects—types of damage considered most harmful to cellular genetic material. The present study is an essential step towards the use of these type of nanomaterials in any biomedical or clinical application.

Carbothermal reduction-induced oxygen vacancies in spinel cathodes for high-performance aqueous zinc-ion batteries

The defect-engineering of low-valent vanadium spinel cathode boost the charge storage performance of aqueous zinc-ion battery.

Spin transport properties of spinel vanadate-based heterostructures

Spin–orbit coupling and breaking of inversion symmetry are necessary ingredients to enable a pure spin current-based manipulation of the magnetization via the spin–orbit torque effect. Currently, magnetic insulator oxides with non-dissipative characteristics are being explored. When combined with non-magnetic heavy metals, known for their large spin–orbit coupling, they offer promising potential for energy-efficient spin-orbitronics applications. The intrinsic electronic correlations characterizing those strongly correlated oxides hold the promises to add extra control-knobs to the desired efficient spin-wave propagation and abrupt magnetization switching phenomena. Spinel vanadate FeV2O4 (FVO) exhibits several structural phase transitions, which are accompanied by an intricate interplay of magnetic, charge, and orbital orderings. When grown as a thin film onto SrTiO3, the compressive strain state induces a perpendicular magnetic anisotropy, making FVO-based heterostructures desirable for spin-orbitronics applications. In this study, we have optimized the deposition of stoichiometric and epitaxial Pt/FVO heterostructures by pulsed laser deposition and examined their spin-related phenomena. From angle-dependent magnetotransport measurements, we observed both anisotropic magnetoresistance and spin Hall magnetoresistance (SMR) effects. Our findings show the SMR component as the primary contributor to the overall magnetoresistance, whose high value of 0.12% is only comparable to properly optimized oxide-based systems.

Anti-site disorder driven short-range order and canted antiferromagnetism in inverse spinel LiNiVO4

Frustration driven short-range magnetic correlations/fluctuations in quantum materials usually host exotic ground states like spin glass, low dimensional magnetism and quantum spin liquid. In this context, different members of spinel (both normal and inverse) family have gained enormous interest and an inverse spinel vanadate, LiNiVO4, seems to be an interesting candidate. Structural investigations reveal that unlike usual cation ordering, Ni and Li ions are randomly distributed at octahedral sites and results in reduced magnetic frustration. Further, an additional anti-site disorder is present, as a small fraction of Ni ions occupies tetrahedral sites. Magnetic susceptibility and heat capacity studies show that short-range magnetic correlations develop below 30 K, followed by a canted antiferromagnetism below 2.2 K. Different competing magnetic interactions due to the presence of disorder and reduced magnetic frustration result in the short-range ordering as well as canted antiferromagnetism in LiNiVO4.

Microstructure and Mineral Phase Evolution of Vanadium Slag by Modulating the CaO/V2O5 Ratio

The slag mineral phase is reconstructed by adding CaO to the molten vanadium slag to obtain a slag with high metallurgical characteristics. In this paper, the effects of the CaO/V2O5 ratio on the microstructure of molten vanadium slag, the phase composition of vanadium slag, and the non-salt roasting-(NH4)2CO3 leaching performance of modified vanadium slag were comprehensively investigated. Molecular dynamics simulation was used to examine the microstructure of the simplified vanadium slag system (FeO-V2Ox-SiO2-CaO) at varied CaO/V2O5 ratios. The results show that V (3+, 4+, and 5+) in the molten vanadium slag is similar to the network former. The V-O structure is dominated by four-fold coordination, and V3+ and V5+ show rich coordination configurations. With the increased CaO content, the overall diffusivity of the system increases, and the network structure is destroyed by CaO. The addition of CaO realizes the mineral phase reconstruction of vanadium slag, and vanadium slag with a more concentrated vanadium distribution and a wider Ca distribution is obtained. The concentration of vanadium in vanadium spinel increases from 17% to 29.4%. A suitable CaO/V2O5 ratio reduces the dependence of the vanadium leaching recovery on the vanadium slag’s roasting temperature and duration.

Doping induced tailoring of properties in polycrystalline spinel vanadate – MnV2O4

We investigate the structural, electronic and magnetic properties of Mn1-xCuxV2O4 (0 ≤ x ≤ 0.1) to study the role of Cu in spinel vanadate MnV2O4. X-ray diffraction studies show the synthesized materials are single phase. However, X-ray photoelectron spectroscopy reveals the presence of cations in more than one valence state. The higher valence states of cations together with the desired ones confirm the presence of excess oxygen in a formula unit and non-stoichiometry increases with increasing Cu content. Further, with increasing Cu content, lattice parameters, unit cell volumes as well as different atomic separations shrink, whereas magnetic transition temperature gradually decreases and the structural transition disappears for x = 0.1. Moreover, magnetic hysteresis loops at 5 K remain unsaturated up to 6 Tesla applied field, whereas coercivity gradually increases and remanent magnetization decreases with increasing Cu content, in tandem with the increasing trend of grain size.

Metamorphic Vanadian–Chromian Spinel (Sludyanka Complex, South Baikal Area). Ferroan Spinel

Abstract —V–Cr-spinel of wide composition range is present as a rock-forming or accessory mineral in parametamorphic rocks of the Sludyanka Complex (South Baikal area, Siberia, Russia). The spinel can be subdivided into two large groups: magnesian spinel and ferroan spinel. In this paper we describe ferroan spinel. It is subdivided into three groups: (1) Zn–V-bearing and vanadian (up to 5 wt.% ZnO and up to 19.5 wt.% V2O3); (2) V-bearing zinc spinel and vanadian zincochromite (up to 6 wt.% V2O3 and 5.0–20.3 wt.% ZnO); and (3) Zn–V spinel and zincochromite (>6 wt.% V2O3 and 5.0–22.2 wt.% ZnO). A separate small group of ferroan spinel is represented by ternary chromite–coulsonite–magnetite solid solution. In addition to the Slyudyanka spinel, we present a summary of metamorphogenic chromium and vanadium spinel from other deposits. The behavior of Cr, V, and Zn in metamorphic and magmatic spinel is discussed.

Synthesis of vanadium nitride from vanadium spinel by synchronous reduction and nitridation with ammonia energy

Synthesis of vanadium nitride from vanadium spinel by synchronous reduction and nitridation with ammonia energy

Spin reorientation in CoV2O4 thin film: A first principles study

Spinel vanadates (AV2O4) are a class of materials where an interesting interplay between spin and orbital degrees of freedom on a frustrated lattice is manifested in the multiple structural and magnetic phase transitions. CoV2O4 is unique among the spinel vanadates as it shows no or very weak cubic to tetragonal structural phase transition but two magnetic (paramagnetic to collinear ferrimagnetic and collinear to noncollinear ferrimagnetic) phase transitions at lower temperatures in its bulk form. In a recent experiment (Thompson et al., Phys. Rev. Mater. 2 (2018) 104411), an epitaxial thin film of CoV2O4 grown on the SrTiO3 (001) substrate, is observed to have an orthorhombic structural phase accompanied by a noncollinear magnetic state where the spin moments of Co and V are reoriented from [001] (seen in the bulk form) to the [110] direction. In this work, we have explored the mechanism behind this complex spin-reorientation and noncollinear magnetic ground state by investigating the electronic structure, magnetic, and structural properties of CoV2O4 in its orthorhombic phase and compared with the corresponding properties of the cubic phase using the first principles density functional theory. Our GGA+U+SO calculations on orthorhombic CoV2O4 reveal that spin moments prefer to lie in the ab-plane with the crystallographic b-direction being the preferred direction in the collinear ferrimagnetic state where it has a larger band gap and orbital moment (of V) as compared to the cases with spin moments aligned parallel to a and c-directions. We further observe competing magnetic exchange interaction values in orthorhombic phase when the spins lie in the ab-plane giving rise to more frustration and hence more canting in the non-collinear magnetic ground stateas compared to the cubic phase, consistent with experiment. With the help of source-free exchange–correlation (XC) functional we were able to capture the non-collinear magnetic ground state and the spin-reorientation in this system. We also discussed the possible orbital ordering in the orthorhombic phase of CoV2O4.

Comparison and evaluation of vanadium extraction from the calcification roasted vanadium slag with carbonation leaching and sulfuric acid leaching

Calcification roasting process for vanadium extraction has advantages in environmental protection, low cost of roasting additives, easy reutilization of the tailings. During the calcification roasting process, the vanadium spinel contained in the converter vanadium slag transforms into calcium vanadate. Carbonation leaching and sulfuric acid leaching used for extracting vanadium from the calcification roasted slag were compared and evaluated in detail, and effects of leaching parameters and the leaching kinetics were investigated. It was found that grinding the roasted slag particles below 94 μm can ensure a higher vanadium recovery. Leaching temperature, concentration of the ammonium carbonate, solid to liquid ratio all impacted the recovery of vanadium significantly. Under the conditions of temperature of 353 K, ammonium carbonate concentration of 200 g/L and solid to liquid ratio of 1:20 g/mL, 73.67% of the vanadium was extracted in 60 min. In the sulfuric acid leaching process, the aqueous pH value played a vital role and it was better to conduct the leaching at temperatures below 323 K. The sulfuric acid leaching reactions progressed fast and under a solid to liquid ratio of 1:10 the leaching efficiency of vanadium reached around 84% at 313 K and pH 2.50 in less than 30 min. Both leaching processes can be well described by the kinetic equation of 1/5(1 − α)−5/3 − 1/4(1 − α)-4/3 + 1/20 = kt, which represents the leaching process is controlled by diffusion of the two reactants in both directions. The difference lies in that the solid layer which the reactants pass through is mainly composed of silicate phases and Fe-rich phases in the ammonium carbonate leaching process, while in the sulfuric acid leaching process, calcium sulfate which instantaneously generates and tightly wraps the unreacted core, plays a dominant role in limiting the diffusion of the reactants. The ammonium carbonate leaching performs better in selectivity over the vanadium than the sulfuric acid leaching, but collection of ammonia and enrichment of vanadium-bearing solution should be considered..

Viscosity calculation for the SiO2[sbnd]CaO-FeO-V2O3−MnO-TiO2 system based on a statistical modeling approach

An accurate and simple viscosity model based on the physically meaningful MYEGA equation has been established for the SiO2CaO-FeO-V2O3−MnO-TiO2 system. The present model accurately predicts the viscosity with an average error (Δ) of 18.76% and root mean square error (RMSE) of 0.108 Pa•s. The composition and temperature dependences of viscosity were discussed. The results show that the vanadium spinel would be precipitated from liquid slag when the viscosity curve enters into the crystalline region. With increasing CaO/SiO2 and FeO/SiO2 mass ratio, the viscosity of molten slag firstly decreases remarkably, subsequently followed by a slight decrease and tended to be stable, implying that FeO and CaO behave similarly in viscous flow. V2O3 behaves as a network former in the network structure and would obviously increase the viscosity. The viscosity generally increases at low SiO2 region and decreases at high SiO2 region with increasing TiO2 content, indicating the amphoteric behavior of TiO2.

Promoting the magnetic exchanges in PLD deposited strained films of FeV2O4 thin films

Transition metal complex oxides are remarkable for the richness of tunable physical properties their strongly correlated electrons allow. We have undertaken the pulsed laser deposition of epitaxial thin films of the magnetically frustrated FeV2O4 spinel vanadate compound. A precise optimization of the oxygen pressure deposition conditions was necessary to avoid the presence of volatile over-oxidated vanadium while avoiding the presence of oxygen vacancies. We report the effect of the epitaxial compressive stress induced by the MgO substrates on the structural and magnetic properties of the films. The surprising films lattice parameters reduction in all directions lead to an unusual auxetic behaviour. The reduced volume of the cell results in a decrease of the V–V distances. This allows a 50 K increase of the magnetic transition temperature, which now reaches 160 K. The epitaxial strain tuning of the magnetic order in the iron-based vanadates open new degrees of freedom towards the integration of the films in oxide electronics.

Vanadium based zinc spinel oxides: Potential materials as photoanode for water oxidation and optoelectronic devices

In the recent past, layered zinc-based vanadium spinel oxides (ZnVOs) have shown an intriguing way to accomplish the challenges of energy conversion, storage, and utilization issues. Here, through first-principles calculations, a comprehensive study has been carried out to investigate the AV2M (where A = Zn, Zn2, Zn3, Zn4, and M = O4, O6, O7, O8, O9 respectively) electronic, photocatalytic, and optical properties. Formation energies with a negative sign express that the final compounds from the pure elements are possible and cohesive energies revealed that compounds are energetically stable. Spin-polarized calculations are also taken into account for better approximation of the electronic properties (band structure and density of states). All layered structures show indirect bandgap for spin-up calculations in range 0.3 eV–2.4 eV, while spin-down calculations show mix trends in range 2.3 eV–3.50 eV. An appropriate band edge with large enough kinetic over-potentials of the oxygen evolution reaction (ΔEV ≥ 1.244 eV) makes them potential candidates as photoanode for water splitting. ZnV2O4 is more suitable for OER as it has small kinetic overpotential as compared to the oxidation potential of water. Interestingly, all ZnVOs display a dramatically large coefficient (~105 cm−1) for optical absorption. Photogenerated electrons and holes on the layered zinc-based vanadium spinel oxide surfaces could make these spinel oxides promising materials for photocatalytic water splitting and solar energy conversion.

Tailoring magnetism in spinel vanadate CoV2O4 epitaxial thin films

Near itinerant cubic bulk CoV2O4 is at variance with other spinel vanadates by not showing orbital ordering down to low temperature, albeit it displays fragile anomalies related to spin, and lattice structure, signaling a spin/orbital glass transition around 95 K. We investigate tetragonal-like epitaxial CoV2O4 films on SrTiO3 and (La0.3Sr0.7)(Al0.65Ta0.35)O3 substrates that exhibit pronounced signature of spin reorientation transition from to a/b plane around 90 K unlike its bulk counterpart. Using in-plane and out-of-plane magnetic measurements, we demonstrate the intricate link between Co2+ and V3+ sublattice magnetizations that give rise to anisotropic magnetic switching. In-plane magnetic measurements reveal a wasp-waist shaped M(H) loop below reorientation transition temperature, while the out-of-plane follows antiferromagnet-like M(H) response. The wasp-waist shaped feature could be linked to in-plane spin-canted (anti)ferromagnetism induced by canting away of V-spins away from antiferromagnetically coupled Co-spin direction below reorientation transition temperature. Further, we uncover the evidence for slow relaxation over a period of ∼104 s at 20 K and memory effect that indicates the possible existence for magnetic glassy phase in the low temperature regime. Using epitaxial strain as a control knob, our results inspire future study to manipulate orbital states, spin texture and itinerant electron character in tailored CoV2O4 films away from cubic lattice symmetry.

Electronic and Magnetic Structure Study of NiV2O4

Inspired by recent experiments and theoretical work on vanadium spinels, the least investigated vanadium spinel i.e. NiV2O4 has been explored theoretically in this work. The systems is found to have an optimized vanadium- vanadium distance of 2.94 , which is the same as the limit of itinerancy in vanadium spinels. This indicates that the system is sitting exactly at the border between metallic and insulating phase. The calculations show that there is no tetragonal distortion present in it and it would prefer normal spinel structure. The DFT calculations have been performed using GGA approximation.

Coulsonite FeV2O4—A Rare Vanadium Spinel Group Mineral in Metamorphosed Massive Sulfide Ores of the Kola Region, Russia

This work presents new data on a rare vanadium spinel group mineral, i.e., coulsonite FeV2O4 established in massive sulfide ores of the Bragino occurrence in the Kola region, Russia. Coulsonite in massive sulfide ores of the Bragino occurrence is one of the most common vanadium minerals. Three varieties of coulsonite were established based on its chemical composition, some physical properties, and mineral association: coulsonite-I, coulsonite-II, and coulsonite-III. Coulsonite-I forms octahedral crystal clusters of up to 500 µm, and has a uniformly high content of Cr2O3 (20–30 wt.%), ZnO (up to 4.5 wt.%), and MnO (2.8 wt.%), high microhardness (743 kg/mm2) and coefficient of reflection. Coulsonite-II was found in relics of quartz–albite veins in association with other vanadium minerals. Its features are a thin tabular shape and enrichment in TiO2 of up to 18 wt.%. Coulsonite-III is the most common variety in massive sulfide ores of the Bragino occurrence. Coulsonite-III forms octahedral crystals of up to 150 µm, crystal clusters, and intergrowths with V-bearing ilmenite, W-V-bearing rutile, Sc-V-bearing senaite, etc. Chemical composition of coulsonite-III is characterized by wide variation of the major compounds—Fe, V, Cr. In some crystals of coulsonite-III, relics of chromite are observed. The microhardness of coulsonite-III is 577 kg/mm2, the reflection coefficient changes in relation to iron, vanadium, and chromium content.

A study on the vibrational frequencies, elastic properties and sound velocities of vanadium spinel oxides AV2O4 (A = Mn, Fe and Zn) short-range non-Coulomb potential theoretical model

Owing to the fact of the AB2O4 spinel oxide’s chemical and thermal stability, and other intriguing properties make them suitable candidate materials for many applications, including chemical looping and catalytic reactions. To do our investigations, a short-range non-Coulomb potential theoretical model is used to calculate the zone-centre, elastic constants, infrared phonon mode frequencies, Raman phonon mode frequencies, velocities of the sound wave along the highly symmetric three crystallographic-axes and Debye temperature of the vanadium spinel oxides AV2O4 (A = Mn, Fe and Zn). The preliminary results of our calculations show that the interaction in the second neighbour (V–O) is much stronger than the interaction of the first neighbour (A–O). Moreover, from the analysis of the obtained results of elastic constants, the nature of the studied vanadium spinels are found to be ductile.

Cleaner extraction of vanadium from vanadium-chromium slag based on MnO2 roasting and manganese recycle

MnO2 roasting was proposed as a suitable roasting method for vanadium extraction from vanadium-chromium slag (V–Cr slag). Acid leaching and vanadium precipitation were carried out for the recovery of vanadium, then V2O5 was prepared. Manganese in the vanadium wastewater could be precipitated and recycled to the next roasting processes. The effects of roasting temperature and the amount of MnO2 on the phase evolution, along with elements distribution and leaching behaviors were discussed by XRD, SEM and leaching experiments. Two methods of manganese recycle were provided and evaluated. Results show that during MnO2 roasting, the stable vanadium spinel was oxidized and combined with Mn2O3, which was the decomposition product of MnO2 to form the acid-soluble manganese vanadate Mn2V2O7. Chromium, on the other hand, was combined with iron to generate the acid-insoluble (Fe0.6Cr0.4)2O3. After leaching the samples roasted at 850 °C in a molar ratio n(MnO)/n(V2O3) of 1.75 with acid at a pH value of 2.5, 89.48% of vanadium and 81.15% of manganese was leached due to the dissolution of Mn2V2O7, while only 0.15% of chromium and 0.02% of iron could be extracted simultaneously, improving the separation efficiency of vanadium with other impurities in V–Cr slag. V2O5 of 99.14% purity was produced after precipitating vanadium and ammonium vanadate roasting. As the highlight stage during MnO2 roasting, manganese could be recycled by precipitating with CO2 in an alkaline environment or precipitating directly with the addition of NH3·H2O. The products of precipitation were MnCO3 and Mn3O4 respectively, which could be both transformed into Mn2O3 before the combination of vanadium and manganese, which is consistent with the reaction during MnO2 roasting.

Computer modeling investigation of MgV2O4 for Mg-ion batteries

MgV2O4 is a vanadium spinel considered for rechargeable magnesium ion batteries. Its defect chemistry, solution of dopants, and the diffusion of Mg ions are investigated using advanced atomistic modeling techniques. The energetically most favorable defect is Mg–V anti-site cluster (0.53 eV/defect) assuming that a small percentage of Mg2+ and V3+ ions would exchange their positions, particularly at higher temperatures. Reaction energies for the loss of MgO via MgO Schottky and the formation of Mg vacancies via Mg Frenkel are calculated to be 5.13 eV/defect and 5.23 eV/defect, respectively, suggesting that the concentrations of these two defects will not be significant. The most favorable diffusion mechanism of Mg ions is a three-dimensional pathway, where the activation energy of migration is 0.52 eV. The formation of Mg interstitials and O vacancies can be facilitated by doping with Co2+ at the V site in MgV2O4. The electronic structures of the favorable dopants calculated using the density functional theory are discussed.