Papers by Keyword: V₂O₅

Abstract: Sintering aids play a crucial role in enhancing the properties of various ceramics, offering benefits such as increased density, lowered sintering temperatures, and changes in material electrical characteristics. This study focuses on investigating the impact of 3 wt.% additions of Bi₂O₃, B₂O₃, and V₂O₅ on the structural, morphological, and electrical properties of hexaferrite SrAlFe₁₁O₁₉ ceramics, known for their significance in microwave applications. Obtained by conventional solid-state synthesis, ceramic samples were subjected to X-ray diffraction (XRD) analysis, Raman spectroscopy, scanning electron microscopy (SEM), and resistivity measurements. Results revealed that the addition of Bi₂O₃ and V₂O₅ effectively reduced porosity in hexaferrite ceramics, which can potentially increase the magnetization values of ferrite material. Notably, the sample with 3 wt.% of B₂O₃ exhibited the highest resistivity, reaching 1.9·10⁷ Ω·cm. These findings suggest that incorporating specific sintering aids can help in achieving controlled conductivity and magnetization in hexaferrite ceramics, which is particularly beneficial for microwave components like inductors, antenna substrates, and circulators.

Abstract: The present study investigated the effect of the sintering temperature and (Y2O3, V2O5) co-doping on the performance of TiO2 varistor ceramic which has lower varistor voltage and high nonlinear coefficient. The results showed that the TiO2-based varistor ceramic which doped with 0.35% mol and 0.25% mol of Y2O3 and V2O5 has good comprehensive electrical performance and excellent dielectric constant sintered at 1200°C. Its varistor voltage V1mA is 38.1V, nonlinear coefficient is 4.6.

Abstract: A systematic investigation of the effect of WO₃ loading over V₂O₅/TiO₂ catalysts was carried out for the selective catalytic reduction of NO by NH₃. The characteristics were examined use BET surface area , X-ray diffractometry (XRD) , Temperature programmed desorption (TPD) of NH₃ . It was fund that the WO₃ species could interact with the TiO₂ anatase phase to exhibits a high activity. With increasing WO₃ content ,the activity of V-W/TiO₂ for the selective catalytic reduction of NO by NH₃ was improved at low temperatures in the range of 3～7%. The results showed that the adding of WO₃ to V₂O₅/TiO₂ could result in exposing acid sites of catalysts doped WO₃ at low temperature. Furthermore, especially the catalytic activity of VW₇Ti showed higher than 80% at 180 °C. However, the catalytic BET surface area and the mass of acid sites not play a leading role for improving low-temperature activity of VWTi in this paper.

Abstract: Due to its outstanding photo-catalysis properties, low-dimensional V₂O₅ has many important applications in lithium ion batteries, supercapacitors, electrochromic devices, photocatalysts, sensors, et al. As good photocatalysts for organic pollutants, some key issues of photocatalysts are charge generation, separation, transfer of nanocomposites under irradiation of visible light. To improve their important properties and pave the effective conductive channels for charge transfer and separation, low-dimensional V₂O₅/graphene nanoribbons nanocomposites were prepared_. The emphasis is put on adsorption response to VOC of nanocomposite based on the QCM (quartz crystal microbalance) device. In order to investigate the mechanism of charge-generated by visible light, the photoconductivity response to visible light and 808 nm laser with low-power were studied based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate. Some good results were obtained. This illustrates that this nanocomposite can easily produce the charge-generate with visible light and 808 nm laser with low-power, avoiding the recombination of charge-generate by light. It would be good applications in remove the organic pollutants with photocatalysis effects.

Abstract: The VN coatings were coated by chemical vapor deposition on T12 substrate using V₂O₅, H₂ and N₂ as reactants. Thermodynamic calculation and analysis of formation reaction of VN were done by thermodynamic potential function. As shown by the experimental results, chemical vapor deposition of the VN coating with preheating temperature of 973K and deposition temperature of 1573K under normal atmospheric pressure was feasible.

Abstract: Cracking and chipping of MnZn Ferrites usually occur during the grinding process although proper additives such as V₂O₅ can restrain development of cracks. To study the mechanisms, the effects of adding V₂O₅ or ZrO₂ to MnZn ferrite were investigated by the rattler test. It was confirmed that adding V₂O₅ could improve the toughness of MnZn ferrite while addition of ZrO₂ showed opposite result. Based on micro-structure analysis, it was found that adding V₂O₅ increased ratio of intergranular fracture mode to the transgranular but adding ZrO₂ caused more transgranular cracks. Besides, V₂O₅ addition changed its grain size distribution and resulted in some larger grains. Possible mechanisms of the toughness improvement were proposed according the above findings.

Abstract: Two catalysts (V₂O₅/AC and V₂O₅/CNTs) with different loadings, prepared by impregnation method, were used to research the DeNOx activity under N₂ and CO₂ atmospheres respecitively at the temperature range from 100°C to 300°C using a fixed bed reactor. Effects of temperature, loading and support on the DeNOx activity were studied. The results show that the NO conversion of the both catalysts increases with the reaction temperature. The loading and support have significant effects on the activities. 9%V₂O₅/AC and 9%V₂O₅/CNTs yielded 80% and 66.6% NO conversion at 250°C respectively under N₂ atmosphere, however, they yielded 78.1% and 75.1% respectively under CO₂ atmosphere.

Abstract: Selective catalytic reduction (SCR) is a well-proven method to reduce NO emission. However, to choose the right catalyst that provides a surface for reaction between NO and ammonia at low temperatures is a challenging task for a catalysts developers. In an earlier study, we prepared V₂O₅-CeO₂-SiO₂ catalyst with increasing V₂O₅ content by sol-gel route and found that the catalytic activity improved with increasing the V₂O₅ loading up to 0.5%. The catalytic activity, however, dropped when V₂O₅ loading was about 1% and increased back when the loading of V₂O₅ was about 5%. In this study, we looked into the microstructural relationship to explain these findings. The microstructures of the catalysts before and after exposure to NO gas revealed that the catalysts with 0.2% and 0.5% V₂O₅ were more porous after the reduction process possibly due to improved breakdown of (NH₄)HCO₃ to NH₃ by the possible interaction with the V₂O₅ and CeO₂-containing catalysts which consequently resulted in a more efficient NO reduction to N₂ and H₂O at low temperature. The microstructure of the catalyst with 1% V₂O₅ content to 5%, improved back the efficiency although clogging by CeVO₄ phase still possible due to its presence based on XRD. The well-ordered micropores before exposure to NO and the more efficient breakdown of (NH₄)HCO₃ could have contributed to increase back the catalytic activity at low temperature.

Abstract: The V₂O₅ films were prepared by the (radio frequency)RF sputtering. The transmission of the samples under different deposition pressures and different Ar/O₂ flow ratios was investigated to determine the fundamental preparation condition for the further analysis. On the fundamental condition, the security volt of V₂O₅ was determined. It is concluded that the annealing makes the V₂O₅ films have a good reversibility but lowers the electrochromic property.

Abstract: The Fe2O3 and V2O5 nanoparticles were prepared by thermal decomposition method. The XRD and FTIR spectrum of the samples confirms the formation of Fe2O3 and V2O5. The FE- SEM images showed the morphology and size of the samples. The synthesized Fe2O3 and V2O5 nanoparticles were used to modify the glassy carbon electrode (GCE) and the modified electrode was found to exhibit electrocatalytic activity for the oxidation of uric acid (UA). It shows that the nanoparticles will exhibit promising applications in the development of sensors.