Effect of Vanadium on Structural and Optical Properties of Borate Glasses Containing Er3+ and Silver Nanoparticles

Glass samples (59.5 – x) B2O3 – 20Na2O – 20CaO – xV2O5 – Er2O3 – 0.5AgCl (x = 0 – 2.5 mol%) were prepared using melt – quenching method to investigate the structural and optical properties of the glass. The structural of the glass were characterized by using XRD, TEM and FTIR, meanwhile the optical properties were characterized by UV – VIS absorption. The XRD patterns confirmed the amorphous nature of the prepared glass samples. FTIR confirmed the presence of VO4, VO5, BO3, and BO4 vibration, and this result showed NBO increased with increasing vanadium concentration. The UV – Vis – NIR spectra exhibits six absorption band centered at 490, 520, 540, 660, 800, and 980 nm. The optical band gap (Eopt), Urbach energy and refractive index shown decrease, increase and increase, respectively. The Judd – Ofelt intensity parameter reveal the trends was Ω2 > Ω4 > Ω6. There are three emission bands at 516 nm, 580 nm, and 673 nm which are represented by 2H11/2 – 4I15/2, 4S3/2 – 4I15/2, and 4F15/2 – 4I15/2, respectively under 800 nm excitation was obtained.

Tailoring the microstructural, magnetic and dielectric properties of vanadium ions substituted nickel ferrite nanocrystals

This paper describes the composition-dependent microstructural, magnetic and dielectric properties of vanadium ions doped nickel ferrite nanoparticles. All the nanoferrite samples (NiV x Fe 2-x O 4 : x = 0.00, 0.05, 0.10 and 0.15) were prepared using conventional co-precipitation method. X-ray diffraction patterns verified the single cubic spinel phase formation and achievement of nano-sized ferrite particles with a homogeneous distribution, which was also supported by HRTEM micrographs. Mean crystallite diameter was seen in the range of 05 nm to 12 nm as evaluated from Williamson-Hall (W-H) curves for the different doped samples. A compressive nature microstrain was noticed in all the samples and was also seen to reduce with the enhancement of vanadium ions content. A blue shift was detected in the indirect band gap for higher vanadium doped samples. Magnetization at the saturation point as well as coercive field both were observed to reduce at room temperature with increasing vanadium concentration in nanosized nickel ferrites. Room temperature dielectric characteristics of all the synthesized samples ensured that the elementary charge conduction process was governed by the hopping of electrons. Cole-Cole plots also showed that the grain boundaries play an important task in deciding the dielectric responses.

Temperature sensitivity modulation through changing the vanadium concentration in a La2MgTiO6:V5+,Cr3+ double perovskite optical thermometer

To fulfil the requirements of operating at low temperature in a harsh environment, the investigation on optical thermometers plays an increasingly important role.

Effects of State of Charge on the Physical Characteristics of V(IV)/V(V) Electrolytes and Membrane for the All Vanadium Flow Battery

The VO2+/VO2+ redox couple commonly employed on the positive terminal of the all-vanadium redox flow battery was investigated at various states of charge (SOC) and H2SO4 supporting electrolyte concentrations. Electron paramagnetic resonance was used to investigate the VO2+ concentration and translational and rotational diffusion coefficient (DT, DR) in both bulk solution and Nafion membranes. Values of DT and DR were relatively unaffected by SOC and on the order of 10−10 m2s−1. Cyclic voltammetry measurements revealed that no significant changes to the redox mechanism were observed as the state of charge increased; however, the mechanism does appear to be affected by H2SO4 concentration. Electron transfer rate (k0) increased by an order of magnitude (10−6 ms−1 to 10−8 ms−1) for each H2SO4 concentrations investigated (1, 3 and 5 M). Analysis of cyclic voltammetry switching currents suggests that the technique might be suitable for fast determination of state of charge if the system is well calibrated. Membrane uptake and permeability measurements show that vanadium absorption and crossover is more dependent on both acid and vanadium concentration than state of charge. Vanadium diffusion in the membrane is about an order of magnitude slower (~10−11 m2s−1) than in solution (~10−10 m2s−1).

Photometrical Determination of the State-of-Charge in Vanadium Redox Flow Batteries Part I: In Combination with Potentiometric Titration

The stepwise oxidation of vanadium ions in electrolytes, as used in all vanadium redox flow batteries (VRFB), is studied offline by a combination of potentiometric titration and simultaneous UV/Vis/NIR spectroscopy. Eight different total vanadium concentrations between 0.2 mol L−1 and 1.6 mol L−1 have been investigated. The analyte (titrand, V2+ solution) is the anolyte (V2+/V3+ side) of a fully charged laboratory vanadium redox flow battery (VRFB). Absorption maxima are observed at λ = 850 nm for V2+ and at λ = 400 nm for V3+, the corresponding absorption coefficients are determined. In the former case an extrapolation procedure is necessary because during transfer from the VRFB to the titration cell, oxidation to V3+ by ambient oxygen cannot completely be avoided. Based on the knowledge of the absorption coefficients, via simultaneous photometry of V2+ and V3+, the state-of-charge of the anolyte of a VRFB can be determined. In the catholyte (V4+/V5+ side) of a VRFB the formation of an intermediate mixed valence VIV–VV complex at large vanadium concentration prevents a simple photometric SOC determination.

Influence of Dietary Vanadium Supplementation on Nutrient Utilisation, Growth Performance and Blood Biochemical Parameters in Sahiwal Calves

An experiment was conducted to examine the effect of dietary vanadium supplementation on feed intake, efficiency of nutrient utilization, growth performance, blood biochemical constituents and endocrine status in male Sahiwal calves. The vanadium concentration in some common feed ingredients was also estimated. Twenty male Sahiwal calves were randomly selected and divided on body weight (71±8.06 kg) and age (6±0.82 months) equalization into 4 different groups (n = 5). The treatments were given with 0, 2, 4 and 8 ppm of vanadium in GP-I, GP-II, GP-III and GP-IV, respectively for a duration of hundred and twenty days and subjected to analysis of variance in completely randomized design (CRD). Green fodder and deoiled seed cakes were found rich in vanadium content than grains and by-products. The dietary supplementation of vanadium did not affect the feed intake, digestibility of nutrients, average daily gain and feed efficiency. Plasma glucose level was increased (plessthan0.05) in GP-III and GP-1V without (p>0.05) affecting insulin level .The total protein, AST and ALT were unaffected by V supplementation. GP-IV showed higher (plessthan0.05) IGF-1 levels, whereas GP-III and GP-1V recorded higher (plessthan 0.05) ALP activity in comparison to GP-I (control) and GP-II. The level of triglycerides decreased in a dose dependent way, however, the cholesterol concentration showed a declining (plessthan 0.05) trend with the increasing vanadium concentration in the diet. It may be concluded that the dietary vanadium supplementation elicits the metabolic profile specially glucose and lipid metabolism of growing calves which in turn may have implications on further growth performance.