V2O5 Doping Research Articles

Tuning the band gap, optical, mechanical, and electrical features of a bio-blend by Cr2O3/V2O5 nanofillers for optoelectronics and energy applications

This work presents a facile approach for controlling the optical and electrical parameters of a biopolymeric matrix for optoelectronics. Vanadium oxide (V2O5) and chromium oxide (Cr2O3) nanoparticles (NPs) were prepared and incorporated into the carboxymethylcellulose/polyethylene glycol (CMC/PEG) blend by simple chemical techniques. Transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD) data showed that V2O5 and Cr2O3 exhibited spherical shapes with sizes in the range of 40–50 nm and 10–20 nm, respectively. In addition, the blend's degree of crystallinity was sensitive to the V2O5 and Cr2O3 doping ratios. The scanning electron microscopy (FE-SEM) and the elemental chemical analysis (EDAX) used to study the filler distribution inside the blend, and confirmed the existence of both V and Cr in the matrix. Fourier transform infrared (FTIR) spectroscopy showed that the dopants significantly affected the blend reactive (C–O–C, OH, and C=O) groups. The stress–strain curves illustrated the reinforcing effect of the dopants up to 1.0 wt\\%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{wt\\%}$$\\end{document} Cr2O3/V. The transmittance and absorption index spectra in the visible-IR wavelengths decreased with increasing filler content. Utilizing Tauc's relation and (optical) dielectric loss, the direct (indirect) band gap narrowed from 5.6 (4.5) eV to 4.7 (3.05) eV at 1.0 wt\\%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{wt\\%}$$\\end{document} Cr2O3/V. All films have an index of refraction in the range of 1.93–2.17. AC conductivity was improved with increasing filler content and temperature. The energy density at 50 °C is in the range of 1–3 J/m3. The influence of V2O5 and Cr2O3 content on the optical conductivity, dielectric constant, loss, and dielectric modulus of CMC/PEG was reported. These enhancements in electrical and optical properties, along with the potential for band gap engineering, offer promising prospects for advanced applications in optoelectronics and energy-related fields.

Effect of ZnO dopant on V2O5:ZnO films electrochromic properties

Due to its unique physical and chemical properties, vanadium pentoxide has become a popular material for electrochromic devices, and using doping with other transition metals can enhance its overall performance. Therefore, the peroxovanadate sol-gel method was used to produce ZnO-doped V2O5 thin films. The results of this work show how ZnO doping affected the electrochromic and structural characteristics of thin films of V2O5. The main finding was that adding ZnO to the V2O5 films improved their cyclic stability and reversibility. Besides that, the incorporation of the dopant resulted in a mixture of crystalline phases, according to the X-ray diffraction. The charge density has increased from 28.79 for undoped to 41.68 mC/cm2 for doped films. The UV–Vis transmittance values between bleached and colored states - ΔT at 633 nm - changed from 14.4 to 55.5% for undoped and doped films, respectively. The roughness (root mean square, RMS) of the film remained the same, i.e., 23.5 ± 4.3 for undoped to 23.8 ± 5.1 nm for doped, as revealed by atomic force microscopy. Finally, the doping of V2O5 with ZnO improved the electrochemical and electrochromic characteristics of these new films, making them promising candidates for electrochromic device applications.

Photocatalytic Methane Conversion: Insight into the Mechanism of C(sp 3 )–H Bond Activation

Photocatalytic Methane Conversion: Insight into the Mechanism of C(sp ³ )–H Bond Activation

Synergistic effect of V2O5 and Bi2O3 on the grain boundary structure of high-frequency NiCuZn ferrite ceramics

High-frequency soft magnetic ferrite ceramics are desired in miniaturized and efficient power electronics but remain extremely challenging to deploy on account of the power loss (Pcv) at megahertz frequencies. Here, we prepared NiCuZn ferrite with superior high-frequency properties by V2O5 and Bi2O3 synergistic doping, which proves to be a potent pathway to reduce Pcv of the ferrite at megahertz frequencies. The sample doped with 800 ppm V2O5 and 800 ppm Bi2O3 yielded the most optimized magnetic properties with a Pcv of 113 kW/m3 (10 MHz, 5 mT, 25 °C), an initial permeability (μi) of 89, and a saturation induction (Bs) of 340 mT, which is at the forefront of the reported results. These outstanding properties are closely related to the notable grain boundary structure, which features a new type of nano-Bi2Fe4O9 phase around ferrite grains and a Ca/Si/V/O amorphous layer. Our results indicate great strides in correlating the grain boundary structure with multiple-ion doping and set the scene for the developing high-frequency soft magnet ferrites.

Investigation of doping effect on electrical conduction mechanism and Li+ ion insertion/extraction in ZnO-XV2O5 {X=5% and 10%} electrode for superior energy storage application

In an effort to enhance the electrical conductivity and electrochemical charge storage capacity of pure ZnO, the multivalent V2O5 is doped with different percentage by solid-state synthesis procedure with low annealing temperature. The materials are characterized by the X-ray diffraction (XRD) and the Fourier Transform Infrared Spectroscopy (FTIR). The XRD pattern reveals hexagonal wurtzite structure with preferred orientation along (101) plane. Three secondary phases Zn3(VO4)2, Zn4V2O9 and ZnV3O8 appear after V2O5 doping. The vibrational bending and stretching modes are identified by the Fourier Transform Infrared Spectroscopy (FTIR). The temperature dependent electrical conduction mechanism of ZnO–V2O5 (ZNV) varistor ceramic materials is studied by ac impedance spectra analysis. The effect of doping on the electrical conductivity formalism was well discussed. By Nearest Neighbor hopping (NNH) model, it is shown that activation energy of ZnO gradually decreased from 0.28 eV to 0.21 eV by introducing V2O5. The electrochemical properties of as prepared ZNV electrodes are investigated by Cyclic voltammetry (CV), Galavanostatic charge-discharge (GCD) and Electrochemical Impedance Spectra (EIS) analysis. In 1 M Li2SO4 electrolyte the ZnO–10%V2O5 (ZNV10) shows maximum specific capacitance 447 F/g at current density 1 A/g. The cyclic stability of pure ZnO, ZnO-5% V2O5 (ZNV5) and ZnO–10%V2O5 (ZNV10) are tested for 1000 cycles. The capacity retention ratio of pure ZnO increases from 68% to 88% after 10% V2O5 doping. The charge storage mechanism of ZNV10 is demonstrated by Faradaic adsorption/desorption through the redox charge transfer process. This work may provide a new scope for further development of pseudocapacitor electrode for high performance supercapacitor.

Optical properties of V, Eu doped sodium borosilicate glass

The effect of different valence state of vanadium ion on the optical properties of V, Eu doped sodium borosilicate glasses were investigated. Diffuse reflectance spectra indicated the increased absorption in 520-1500 nm by increasing the vanadium concentration with V2O3 or V2O5 doping into the glass. Equimolar V2O3 and V2O5 displayed same absorption edge in the glass and shifted the edge to longer wavelength. Incorporation of the Eu2O3 produces characteristic absorption peaks of Eu3+ without affecting the absorption edge of the glass. The lower concentration of V2O5 in glass showed the least absorption and relatively strongest emission at ∼526 nm, indicating the existence of V4+ playing a quenching role. In codoped Eu2O3 and V2O3 (or V2O5) glass, the emission intensity of the Eu3+ (red emission) or V2O5 (blue-green emission) decreases to a large extent, indicating quenching of V5+ emission by V4+ and weak exchange energy transfer from V5+ to Eu3+. 80-473 K temperature dependent emission spectra with 325 nm laser excitation, elemental mapping, and lifetime decay measurement for V/Eu doped glass samples have also been investigated.

Elastic Properties of Vanadium Doped Silica-Borotellurite Glasses

Silica borotellurite glasses doped with different molar fraction of V2O5 have been prepared by melt quenching technique. The elastic properties of {[(TeO2)0.7 (B2O3)0.3]0.8(SiO2)0.2}(1-x)(V2O5)x glasses are investigated using ultrasonic pulse echo measurements and their elastic properties have been characterized at room temperature. The density of the glasses was measured by Archimedes method using distilled water as buoyant liquid. The ultrasonic wave velocities (longitudinal, vl and shear, vS) were recorded at 5 MHz. Elastic moduli, Poisson’s ratio (σ) and microhardness (H) were then calculated to obtain quantitative analysis regarding the structure of these glasses. The results obtained showed that the doping of V2O5 with silica borotellurite enhances the strengthening of glass network. Glass with 0.03 molar fraction of V205 shows low ultrasonic velocities and low elastic moduli. The variation of elastic properties is related to the change of structure in the vanadium doped silica-borotellurite glass system.

Strong spin-orbit interaction induced by transition metal oxides at the surface of hydrogen-terminated diamond

Hydrogen-terminated diamond possesses an intriguing p-type surface conductivity which is induced via thermodynamically driven electron transfer from the diamond surface into surface acceptors such as atmospheric adsorbates, a process called surface transfer doping. High electron affinity transition metal oxides (TMOs) including MoO3 and V2O5 have been shown to be highly effective solid-state surface acceptors for diamond, giving rise to a sub-surface two-dimensional (2D) hole layer with metallic conduction. In this work, low temperature magnetotransport is used as a tool to show the presence of a Rashba-type spin-orbit interaction with a high spin-orbit coupling of 19.9 meV for MoO3 doping and 22.9 meV for V2O5 doping, respectively, through the observation of a transition in the phase-coherent backscattering transport from weak localization to weak antilocalization at low temperature. Surface transfer doping of diamond with TMOs provides a 2D hole system with spin-orbit coupling that is over two times larger than that reported for diamond surfaces with atmospheric acceptors, opening up possibilities to study and engineer spin transport in a carbon material system.

Effect of Superhalogen Anions on the Electrochemical Behavior of V2O5 Electrodes in Redox Reactions with Lithium in EC-DMC/Li-Salt Solutions

It was established that the number of active sites for the insertion/extraction of lithium ions in/from the V2O5 structure in EC-DMC/Li-salt solutions depends on superhalogen anion. Unstable sites and their dependence on superhalogen anion (PF6 –, AsF6 –, ClO4 –) are identified during discharge-charge cycling of V2O5 electrodes. The number of open sites in V2O5 depends on the structure stability and conductivity of V2O5. To increase the structure stability in phase transitions, we propose the electrochemical doping of V2O5 by Mn2+. We propose that the conductivity and rate characteristics of V2O5 could be increased by its co-deposition with conducting polymer of polyaniline type. Using theoretical calculation simulations assumptions have been made regarding the difference in the solvation of lithium ions in an EC/DMC mixture with different ratios of the solvents.

Chemisorption and kinetic mechanisms of elemental mercury on immobilized V2O5/TiO2 at low temperatures.

To investigate the effect of low temperature and catalyst filling pattern on the adsorption of Hg° by DeNOx equipment, the chemisorption and kinetic mechanisms of Hg° adsorption on 5-30%V2O5/TiO2 immobilized on glass beads at 100-160 °C were investigated. The effects of the reaction temperature, influent Hg° concentration, and V2O5 doping amount on the adsorption efficiency and capacity for Hg° were explored. The active sites for Hg° adsorption were further identified. Additionally, the adsorption kinetics were modelled using the linear driving force approximation, Fick's diffusion model, and pseudo-second-order kinetic model. Finally, the influence of immobilization on the adsorption of Hg° was also investigated. Experimental results showed that the bridged oxygen atom of V-O-V played a key role in the adsorption of Hg°. The Hg° adsorption efficiencies decreased from >90% to 40% as the reaction temperature increased from 120 °C to 160 °C for 20%V2O5/TiO2, while the adsorptive capacities for Hg° were highly influenced by the influent Hg° concentration and V2O5 doping amount. 20%V2O5/TiO2 had the highest adsorptive capacity of 2547 μg Hg°/g V2O5/TiO2 at 160 °C. The kinetic results showed that the linear driving force approximation model fit the Hg° adsorption better than the other models. The diffusion resistance increased significantly for the immobilized catalysts because the external mass transfer coefficient decreased by more than 1200-fold.

Effects of V2O5 doping on the structure and electrical properties of BCZT lead-free piezoelectric ceramics

Lead-free (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3-x mol%V2O5 (x = 0, 0.05, 0.15, 0.20 and 0.50) were fabricated successfully via solid-state reaction route and the effects of V2O5 doping on the phase composition, microstructure and electrical properties of the ceramics have also been studied. The results indicated that the addition of V2O5 significantly lower the sintering temperature of BCZT ceramics to 1350 °C without sacrificing the high piezoelectrical properties. XRD results revealed that the phase structure was not changed with the introduction of V2O5. The sinterablity results and the SEM graphs indicated that small amount of V2O5 could effectively increase the density and grain size of BCZT ceramics. However, the electrical properties of BCZT ceramics deteriorate rapidly when the amount of V2O5 up to 0.5 mol%. Thus, the piezoelectrical properties of BCZT-xV ceramics could be obtained at x = 0.2 mol%, which were as following: d33 = 466 pC/N, kp = 32.5%, Qm = 162, Pr = 7.735 µC/cm2, er = 3104 and tan δ = 0.03, implying promising applications for lead-free piezoelectric ceramics.

Physical, optical and morphological studies of V2O5 doped zinc lead lithium phosphate (ZnPbLiP) glasses

Abstract Vanadium ion doped zinc lead lithium phosphate glass samples are prepared by melt quench method. X-ray diffraction studies confirmed the amorphous nature of all the prepared glasses. The density and refractive index values of these glasses are evaluated using the Archimedes method and Abbe’s refractometer respectively. The values of density found to be in between 3.6363 and 3.6666 g/cm3. The refractive index values are observed in the range 1.5605–1.5620. An increasing trend has been observed in density and refractive index from the simultaneous variation of Li2CO3 and V2O5 in the host matrix. Optical absorption spectra of these samples exhibited two absorption bands at 548 and 738 nm which indicate the characteristic absorption peaks of V4+ ions. The optical basicity values of the studied glasses V1–V5 are identified to slightly vary from 0.6736 to 0.6718, which represents electron donor ability of oxide ions to the cations. The knowledge on optical basicity finds immediate applications in the design of the novel optical functional materials like polarizers, detectors and modulators with higher optical performance. The morphological variations have been observed in the studied glasses upon doping of V2O5 by using Scanning Electron Microscopy.

Effects of V<sub>2</sub>O<sub>5</sub> Addition on Microwave Dielectric Properties of Li<sub>2</sub>ZnTi<sub>3</sub>O<sub>8</sub> Ceramics for LTCC Applications

The sintering temperature of Li2ZnTi3O8 ceramics is still high for LTCC-based applications. In this work, V2O5 was doped as the sintering aid. The sintered density, phase composition, grain size, as well as microwave dielectric properties of Li2ZnTi3O8 ceramics with the addition of V2O5 were investigated. Based on our research, V2O5 doping effectively promoted the densification of Li2ZnTi3O8 ceramics at about 900°C, without affecting the main crystal phase of the ceramics. Li2ZnTi3O8 ceramics with 0.5 wt% V2O5 doping (sintered at 900°C) exhibited the best microwave dielectric properties (Qf = 22,400 GHz at about 6 GHz, er = 25.5, and τf = -10.8 ppm/°C). The V2O5-doped Li2ZnTi3O8 ceramics were well cofired with Ag inner paste without cracks and diffusion, indicating its significant potential for LTCC applications.

Vanadium doping for lowering the preparation temperatures of CaCu3Ti4O12 ceramics and its effect on their microstructures and dielectric properties

Because of their colossal dielectric constant, CaCu3Ti4O12 ceramics have promising applications for cofired multilayer ceramic capacitors. However, their preparation temperature is still too high for such type of applications. This work demonstrates that V2O5 doping can considerably lower the calcination and sintering temperatures of CaCu3Ti4O12 ceramics. Herein, the CaCu3Ti4O12 ceramics, partially substituted by V5+ for Ti4+ with a molecular formula of CaCu3Ti4−xVxO12 (x = 0, 0.01, 0.03, 0.05), were prepared by the solid state reaction method using V2O5 as the doping substance. It has been shown that V2O5 can considerably lower the calcination and sintering temperatures to 870 and 950 °C, respectively. The dielectric constant of the low temperature prepared CaCu3Ti4−xVxO12 ceramics is much larger than the undoped CaCu3Ti4O12. This work provides a preliminary step for possible commercial applications of CaCu3Ti4O12 ceramics for cofired multilayer ceramic capacitors.

Structural and electronic properties of V2O5 and their tuning by doping with 3d elements - modelling using the DFT+U method and dispersion correction.

New electrode materials for alkaline-ion batteries are a timely topic. Among many promising candidates, V2O5 is one of the most interesting cathode materials. While having very high theoretical capacity, in practice, its performance is hindered by its low stability and poor conductivity. As regards the theoretical descriptions of V2O5, common DFT-GGA calculations fail to reproduce both the electronic and crystal structures. While the band gap is underestimated, the interlayer spacing is overestimated as weak dispersion interactions are not properly described within GGA. Here we show that the combination of the DFT+U method and semi-empirical D2 correction can compensate for the drawbacks of the GGA when it comes to the modelling of V2O5. When compared to common PBE calculations, with a modest increase in the computational cost, PBE+U+D2 fully reproduced the experimental band gap of V2O5, while the errors in the lattice parameters are only a few percent. Using the proposed PBE+U+D2 methodology we studied the doping of V2O5 with 3d elements (from Sc to Zn). We show that both the structural and electronic parameters are affected by doping. Most importantly, a significant increase in conductivity is expected upon doping, which is of great importance for the application of V2O5 in metal-ion batteries.

New thin films of NiO doped with V2O5 for electrochromic applications

This paper reports on synthesis and characterization of new electrochromic thin films of NiO doped with V2O5 that were prepared by the sol-gel method and deposited by the spin coating technique. The confirmation of the presence of the dopant in the structure of the films was given by energy-dispersive X-ray spectroscopy (EDX). The effect of the addition of vanadium to the films of NiO was evaluated by electrochemical techniques such as cyclic voltammetry, chronocoulometry, and chronoamperometry in 0.5 mol/L KOH electrolyte. The morphology and the structure of the films, determined by microscopies (SEM and AFM), reveal smooth and slightly rough surfaces. The addition of vanadium as a dopant does not produce changes in the host NiO matrix as evidenced by X-ray diffractometry (XRD). However, the addition of the dopant causes a significant improvement in a charge density values of the films that increase more than twice from 25.5 mC/cm2 for NiO to 52.8 mC/cm2 for NiO with 10 mol% of V2O5. V2O5 doping of NiO films also improved their optical properties as well as kinetics of insertion and extraction processes.

Designing vanadium pentoxide-carboxymethyl cellulose/polyvinyl alcohol-based bionanocomposite films and study of their structure, topography, mechanical, electrical and optical behavior

In the present work, thin films of carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) were prepared by solution casting method and vanadium pentoxide (V2O5) was doped by in situ precipitation to yield CMC/PVA-V2O5 bionanocomposites. The materials were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), and Fourier transform infrared (FTIR) techniques and AC/DC conductivity, tensile strength, and microhardness measurements, and photo-luminescence (PL) and UV–Vis spectroscopic studies were conducted. The results of AFM and XRD studies provided information about morphology and crystalline features of the bionanocomposite film, respectively. The FTIR spectroscopy confirmed the presence of functional groups of the constituent polymers in the bionanocomposite and showed that V2O5 was successfully incorporated into CMC/PVA matrix. The AFM analysis of bionanocomposite films provided information about their morphology and roughness parameters. The PL spectroscopy indicated the appearance of blue shift after doping of V2O5 into the biopolymer film. The AC electrical conductivity was measured in the range 500–100,000 Hz and it was found that at room temperature the conductivity increases with frequency. Differential scanning calorimetry was used to look into the possible thermal transitions occurring in the bionanocomposites.

Study of Undoped and V2O5 Doped Polythiophene thin Films by Chemical Bath Deposition Technique

Study of Undoped and V2O5 Doped Polythiophene thin Films by Chemical Bath Deposition Technique

Effect of V2O5 doping on p- to n-conduction type transition of TiO2:WO3 composite humidity sensors

Actually, humidity sensors have got multiplying applications from the industrial processing to the environmental control, mainly those based on semiconducting metal oxides. Certain ceramic oxides or composite oxides are wide-bandgap semiconductors and the overall conduction mechanisms are highly influenced by the sensing material physical/chemical properties. For the humidity measurement (relative humidity (RH)), the electronic/ionic charge transfer reactions that take place at the semiconductor surface can be used for this purpose.It is well recognized that water molecules are observed to increase the conductivity of n-type ceramics and to decrease the conductivity of p-type ceramics. Nevertheless several mechanisms have been proposed to explain electrical response variations of oxide metals of with humidity.The present paper describes part of the work that is being carried out to investigate the effect of doping metals oxides on TiO2:WO3 bulk sensors humidity response.For that the V2O5 ceramic was selected. The influence of different contents, 3, 5 and 7 percentage in weight, were investigated concerning microstructural characterization and their electrical response was measured in the range 400Hz–40MHz, at operating temperatures of 20 and 30°C and on the relative humidity (RH) range between 10 and 100%. For all doped sensors a p- to n-conduction transition was found, and the best humidity response was observed for the sensor containing 3 percentage in weight of oxide doping. Besides a new non-classical model for the doped sensors electrical behaviour with moisture is depicted, which allow to better comprehend the diverse phenomena present in our sensors contributing to the overall electrical response.

Influence of Dopant Concentration on the Electrochromic Properties of Tungsten Oxide Thin Films

In order to achieve neutral coloration suitable for smart window applications WO3 thin films modified by V2O5 doping were deposited using RF magnetron sputtering method with 100W RF power at room temperature (RT). The influence of dopant concentration on the structural and electrochromic performance have been investigated. Amorphous structure was revealed by the surface characteristics facilitates electrochromic process. Uniformly distributed channels between the aggregated grains provide shorter path ways to enhance coloration efficiency. PL emission presented higher photonic efficiency for 2% of V2O5 doped WO3 film. Reversible color change between transparent oxidized and deep blue colored reduced state depicted faster ion intercalation / deintercalation kinetics and faster switching responses with the bleaching time of 3.3s and coloration time of 4.1s. Better reversibility of 59.10 %, larger photopic contrast ratio of 2.29 and greater coloration efficiency of 66.75cm2C−1 at 630nm unveiled by 2% of V2O5 doping, makes the film promising for practical applications.