Showing papers on "Vanadate published in 2012"
TL;DR: Novel medicinal potentiality of vanadium compounds is geared towards endemic diseases in tropical countries, in particular leishmaniasis, Chagas' disease and amoebiasis, and viral infections such as Dengue fever, SARS and HIV.
Abstract: In the early treatment of diabetes with vanadium, inorganic vanadium compounds have been the focus of attention; organic vanadium compounds are nowadays increasingly attracting attention. A key compound is bis(maltolato)oxidovanadium, which became introduced into clinical tests Phase IIa. Organic ligands help modulate the bioavailability, transport and targeting mechanism of a vanadium compound. Commonly, however, the active onsite species is vanadyl (VO(2+)) or vanadate (H(2)VO(4) (-)), generated by biospeciation. The mode of operation can be ascribed to interaction of vanadate with phosphatases and kinases, and to modulation of the level of reactive oxygen species interfering with phosphatases and/or DNA. This operating mode has also been inferred for most cancerostatic vanadium compounds, although some, for example vanadocenes, may directly intercalate with DNA. Novel medicinal potentiality of vanadium compounds is geared towards endemic diseases in tropical countries, in particular leishmaniasis, Chagas' disease and amoebiasis, and viral infections such as Dengue fever, SARS and HIV.
180 citations
TL;DR: In this paper, the electronic structure of four ternary-metal oxides containing isolated vanadate ions is studied by high-pressure optical-absorption measurements up to 20 GPa.
Abstract: The electronic structure of four ternary-metal oxides containing isolated vanadate ions is studied. Zircon-type YVO4, YbVO4, LuVO4, and NdVO4 are investigated by high-pressure optical-absorption measurements up to 20 GPa. First-principles calculations based on density-functional theory were also performed to analyze the electronic band structure as a function of pressure. The electronic structure near the Fermi level originates largely from molecular orbitals of the vanadate ion, but cation substitution influence these electronic states. The studied ortovanadates, with the exception of NdVO4, undergo a zircon-scheelite structural phase transition that causes a collapse of the band-gap energy. The pressure coefficient dEg/dP show positive values for the zircon phase and negative values for the scheelite phase. NdVO4 undergoes a zircon-monazite-scheelite structural sequence with two associated band-gap collapses.
127 citations
TL;DR: Luminescence and its decay lifetime studies confirm the decrease in non-radiative transition probability with the increase of heat treatment temperature and a possible reaction mechanism at different pH values is suggested in this study.
Abstract: GdVO4 : Ln3+ (Ln3+ = Dy3+, Eu3+, Sm3+, Tm3+) nanoparticles are prepared by a simple chemical route at 140 °C. The crystallite size can be tuned by varying the pH of the reaction medium. Interestingly, the crystallite size is found to increase significantly when pH increases from 6 to 12. This is related to slower nucleation of the GdVO4 formation with increase of VO43− present in solution. The luminescence study shows an efficient energy transfer from vanadate absorption of GdVO4 to Ln3+ and thereby enhanced emissions are obtained. A possible reaction mechanism at different pH values is suggested in this study. As-prepared samples are well dispersed in ethanol, methanol and water, and can be incorporated into polymer films. Luminescence and its decay lifetime studies confirm the decrease in non-radiative transition probability with the increase of heat treatment temperature. Re-dispersed particles will be useful in potential applications of life science and the film will be useful in display devices.
85 citations
Abstract: The ac conductivity of bismuth zinc vanadate glasses with compositions 50V2O5. xBi2O3. (50-x) ZnO has been studied in the frequency range 10−1 Hz to 2 MHz and in temperature range 333.16 K to 533.16 K. The temperature and frequency dependent conductivity is found to obey Jonscher's universal power law for all the compositions of bismuth zinc vanadate glass system. The dc conductivity (σdc), crossover frequency (ωH), and frequency exponent (s) have been estimated from the fitting of experimental data of ac conductivity with Jonscher's universal power law. Enthalpy to dissociate the cation from its original site next to a charge compensating center (Hf) and enthalpy of migration (Hm) have also been estimated. It has been observed that mobility of charge carriers and ac conductivity in case of zinc vanadate glass system increases with increase in Bi2O3 content. In order to determine the conduction mechanism, the ac conductivity and its frequency exponent have been analyzed in the frame work of various theore...
82 citations
TL;DR: A disordered rock-salt-type structure Li2VO3, a cathode material for Li ion batteries, is easily formed through lithium insertion into LiVO3 as discussed by the authors.
Abstract: A disordered rock-salt-type structure Li2VO3, a cathode material for Li ion batteries, is easily formed through lithium insertion into LiVO3.
80 citations
TL;DR: It is demonstrated that decameric niobate and vanadate species are stronger inhibitors of the SR calcium ATPase than simple monomericVanadate, tungstate and molybdate oxometalates, thus affecting calcium homeostasis, cell signalling and cell bioenergetics, as well many other cellular processes.
58 citations
TL;DR: In this paper, the analysis of the spectroscopic data in combination with the XRD results has been shown that vanadate anion, which substitutes nitrate at the anion exchange, is pyrovanadate, V 2 O 7 4 -.
56 citations
TL;DR: In this article, a 50% yield of 2 was achieved in a 2-h reaction at 80°C, with a turnover number being higher than 1200, in the presence of the n-Bu4NVO3/pyrazine-2-carboxylic acid catalytic combination.
Abstract: Isoeugenol [2-methoxy-4-(prop-1-en-1-yl)phenol; compound 1] can be oxidized to vanillin (4-hydroxy-3-methoxybenzaldehyde, compound 2) by H2O2 in the presence of the n-Bu4NVO3/pyrazine-2-carboxylic acid catalytic combination. A 50% yield of 2 was attained in a 2-h reaction at 80 °C, with a turnover number being higher than 1200. Kinetics of the transformation of 1 into 2 have been studied. The results obtained indicate that the first step of the 1 activation is its interaction with a hydroxyl radical. Further transformations of the primary product formed in this step proceed via several routes, one of which leads to the formation of 2. It has been proposed that the interaction of vanadate with the first molecule of H2O2 gives a V(IV)-containing species and hydroperoxyl radical: “VV–OOH” → “VIV” + HOO . In the next step, the V(IV) complex reacts with the second molecule of H2O2 affording a hydroxyl radical and recovering a starting V(V)-containing species: “VIV” + H2O2 → “VV” + HO− + HO . Then, the hydroxyl radical attacks a double bond in the substrate: HO + CHR′ CHR″ → C HR′–CH(OH)R″. The carbon-centered radical formed in the latter step can rapidly capture a molecule of O2 from the atmosphere: C HR′–CH(OH)R″ + O2 → C(OO )HR′–CH(OH)R″. Finally, a rupture of the C C bond gives rise to the formation of aldehyde 2.
50 citations
TL;DR: In this paper, the adsorption process of calcined Mg/Al hydrotalcite was mainly anion exchange and adorption on external surface of the layers.
48 citations
TL;DR: In this paper, the photonic stop bands (PSB) of the inverse opal photonic crystals of the YVO4:Dy3+ (n = 1.98) were controlled on the emissions of yellow (4F9/2-6H13/2) and blue (4 F9/1-2−6H15/2), respectively, and strong modification on steady-state emission spectra and luminescent dynamics were observed at room temperature.
Abstract: In this article, we first fabricate YVO4:Dy3+ (n = 1.98) inverse opal photonic crystals (PCs) through the polymethylmethacrylate (PMMA) template and the photonic stop bands (PSB) of the PCs controlled on the emissions of yellow (4F9/2–6H13/2) and blue (4F9/2–6H15/2) of Dy3+, respectively. Strong modification on steady-state emission spectra and luminescent dynamics are observed at room temperature. It is interesting to observe that the spontaneous emission rates (SER) of the PCs are suppressed as high as 230–250% in contrast to the reference grinded powder samples (REF) due to the change of effective refractive index (neff). The more significant, the studies on the temperature-dependent emissions indicate that in the inverse opals, the long-scale energy transfer (ET) among Dy3+ ions and vanadate groups is greatly inhibited, and thus the temperature-quenching of photoluminescence (PL) is considerably suppressed. As a consequence, the luminescent quantum yield of the YVO4:Dy3+ inverse opals increases greate...
44 citations
TL;DR: Variation in the vanadate concentration in the obtained YPO(4):Eu(3+) phosphors enabled the establishment of a strict correlation between the observable spectroscopic features and the chemical characteristics of the powders.
Abstract: Nanosized rare earth phosphovanadate phosphors (Y(P,V)O4:Eu3+) have been prepared by applying the organic–inorganic polymeric precursors methodology. Luminescent powders with tetragonal structure and different vanadate concentrations (0%, 1%, 5%, 10%, 20%, 50%, and 100%, with regard to the phosphate content) were then obtained for evaluation of their structural and spectroscopic properties. The solids were characterized by scanning electron microscopy, X-ray diffractometry, vibrational spectroscopy (Raman and infrared), and electronic spectroscopy (emission, excitation, luminescence lifetimes, chromaticity, quantum efficiencies, and Judd–Ofelt intensity parameters). The solids exhibited very intense 5D0 → 7FJ Eu3+ transitions, and it was possible to control the luminescent characteristics, such as excitation maximum, lifetime and emission colour, through the vanadium(V) concentration. The observed luminescent properties correlated to the characteristics of the chemical environments around the Eu3+ ions with respect to the composition of the phosphovanadates. The Eu3+ luminescence spectroscopy results indicated that the presence of larger vanadium(V) amounts in the phosphate host lattice led to more covalent and polarizable chemical environments. So, besides allowing for control of the luminescent properties of the solids, the variation in the vanadate concentration in the obtained YPO4:Eu3+ phosphors enabled the establishment of a strict correlation between the observable spectroscopic features and the chemical characteristics of the powders.
TL;DR: In this paper, the vanadate film with better corrosion resistance forms on Mg-Li-Al-Ce surface after the sample is immersed in 30 g L −1 NH 4 VO 3 ǫ+3.75 g L−1 K 3 (Fe(CN) 6 ) solution at 80°C for 10 min.
TL;DR: It is suggested that ROS formation is unlikely to be involved in the biological function of tungstate and molybdate, whereas the redox properties of vanadium may be important factors for it to exert pharmacological effects.
Abstract: The differential antiproliferative effects of vanadate, tungstate, and molybdate on human prostate cancer cell line PC-3 were compared and the underlying mechanisms were investigated. The results demonstrate that all of the three oxoanions can cause G2/M cell cycle arrest, which is evidenced by the increase in the level of phosphorylated Cdc2 at its inactive Tyr-15 site. Moreover, even if the difference in cellular uptake among the three oxoanions is excluded from the possible factors affecting their antiproliferative activity, vanadate exerted a much more potent effect in PC-3 cells than the other two oxoanions. Our results also reveal that reactive oxygen species (ROS)-mediated degradation of Cdc25C rather than Cdc25A or Cdc25B is responsible for vanadate-induced G2/M cell cycle arrest. We propose a possible mechanism to clarify the differential effect of the three oxoanions in biological systems beyond just considering that they are structural analogs of phosphate. We suggest that ROS formation is unlikely to be involved in the biological function of tungstate and molybdate, whereas the redox properties of vanadium may be important factors for it to exert pharmacological effects. Further, given the evidence from epidemiology studies of the association between diabetes and prostate cancer, the possibility of vanadate as a good candidate as both an antidiabetic and an anticancer agent or a chemopreventive agent is indicated.
TL;DR: The ability of V(10) to inhibit the Ca(2+)-ATPase may be at least in part due to the process of vanadate reduction and associated protein cysteine oxidation.
Abstract: Recently we demonstrated that the decavanadate (V10) ion is a stronger Ca2+-ATPase inhibitor than other oxometalates, such as the isoelectronic and isostructural decaniobate ion, and the tungstate and molybdate monomer ions, and that it binds to this protein with a 1 : 1 stoichiometry. The V10 interaction is not affected by any of the protein conformations that occur during the process of calcium translocation (i.e. E1, E1P, E2 and E2P) (Fraqueza et al., J. Inorg. Biochem., 2012). In the present study, we further explore this subject, and we can now show that the decaniobate ion, [Nb10 = Nb10O28]6−, is a useful tool in deducing the interaction and the non-competitive Ca2+-ATPase inhibition by the decavanadate ion [V10 = V10O28]6−. Moreover, decavanadate and vanadate induce protein cysteine oxidation whereas no effects were detected for the decaniobate, tungstate or molybdate ions. The presence of the antioxidant quercetin prevents cysteine oxidation, but not ATPase inhibition, by vanadate or decavanadate. Definitive V(IV) EPR spectra were observed for decavanadate in the presence of sarcoplasmic reticulum Ca2+-ATPase, indicating a vanadate reduction at some stage of the protein interaction. Raman spectroscopy clearly shows that the protein conformation changes that are induced by V10, Nb10 and vanadate are different from the ones induced by molybdate and tungstate monomer ions. Here, Mo and W cause changes similar to those by phosphate, yielding changes similar to the E1P protein conformation. The putative reduction of vanadium(V) to vanadium(IV) and the non-competitive binding of the V10 and Nb10 decametalates may explain the differences in the Raman spectra compared to those seen in the presence of molybdate or tungstate. Putting it all together, we suggest that the ability of V10 to inhibit the Ca2+-ATPase may be at least in part due to the process of vanadate reduction and associated protein cysteine oxidation. These results contribute to the understanding and application of these families of mono- and polyoxometalates as effective modulators of many biological processes, particularly those associated with calcium homeostasis.
TL;DR: The analysis of the molecular properties of Gly-Ser and their change upon different modes of coordination to the vanadate pointed out that only in Complex 2 the amide carbon is suitable for attack by the hydroxyl group in the Ser side chain, which acts as an effective nucleophile.
Abstract: Hydrolysis of dipeptides glycylserine (Gly-Ser), leucylserine (Leu-Ser), histidylserine (His-Ser), glycylalanine (Gly-Ala), and serylglycine (Ser-Gly) was examined in vanadate solutions by means of (1)H, (13)C, and (51)V NMR spectroscopy. In the presence of a mixture of oxovanadates, the hydrolysis of the peptide bond in Gly-Ser proceeds under the physiological pH and temperature (37 °C, pD 7.4) with a rate constant of 8.9 × 10(-8) s(-1). NMR and EPR spectra did not show evidence for the formation of paramagnetic species, excluding the possibility of V(V) reduction to V(IV) and indicating that the cleavage of the peptide bond is purely hydrolytic. The pD dependence of k(obs) exhibits a bell-shaped profile, with the fastest hydrolysis observed at pD 7.4. Combined (1)H, (13)C, and (51)V NMR experiments revealed formation of three complexes between Gly-Ser and vanadate, of which only one complex, designated Complex 2, formed via coordination of amide oxygen and amino nitrogen to vanadate, is proposed to be hydrolytically active. Kinetic experiments at pD 7.4 performed by using a fixed amount of Gly-Ser and increasing amounts of Na(3)VO(4) allowed calculation of the formation constant for the Gly-Ser/VO(4)(3-) complex (K(f) = 16.1 M(-1)). The structure of the hydrolytically active Complex 2 is suggested also on the basis of DFT calculations. The energy difference between Complex 2 and the major complex detected in the reaction mixture, Complex 1, is calculated to be 7.1 kcal/mol in favor of the latter. The analysis of the molecular properties of Gly-Ser and their change upon different modes of coordination to the vanadate pointed out that only in Complex 2 the amide carbon is suitable for attack by the hydroxyl group in the Ser side chain, which acts as an effective nucleophile. The origin of the hydrolytic activity of vanadate is most likely a combination of the polarization of amide oxygen in Gly-Ser due to the binding to vanadate, followed by the intramolecular attack of the Ser hydroxyl group.
TL;DR: By affecting actin structure and function, vanadium can regulate many cellular processes of great physiological significance and it is suggested that actin might be a potential target not only for decavanadate but above all for vanadyl.
Abstract: spectroscopy, reveals a 1 : 1 binding stoichiometry and a Kd of 7.5 mM � 1 . Both decavanadate and vanadyl inhibited G-actin polymerization into actin filaments (F-actin), with a IC50 of 68 and 300 mM, respectively, as analysed by light scattering assays, whereas no effects were detected for vanadate up to 2 mM. However, only vanadyl (up to 200 mM) induces 100% of G-actin intrinsic fluorescence quenching, whereas decavanadate shows an opposite effect, which suggests the presence of vanadyl high affinity actin binding sites. Decavanadate increases (2.6-fold) the actin hydrophobic surface, evaluated using the ANSA probe, whereas vanadyl decreases it (15%). Both vanadium species increased the e-ATP exchange rate (k = 6.5 � 10 � 3 s � 1 and 4.47 � 10 � 3 s � 1 for decavanadate and vanadyl, respectively). Finally, 1 H NMR spectra of G-actin treated with 0.1 mM decavanadate clearly indicate that major alterations occur in protein structure, which are much less visible in the presence of ATP, confirming the preventive effect of the nucleotide on the decavanadate interaction with the protein. Putting it all together, it is suggested that actin, which is involved in many cellular processes, might be a potential target not only for decavanadate but above all for vanadyl. By affecting actin structure and function, vanadium can regulate many cellular processes of great physiological significance.
TL;DR: Findings support the notion that the FOXO1-PGC-1α complex is involved in the control of ALAS1 expression and suggest further that a vanadate-based therapy could be beneficial for the treatment of acute porphyria attacks.
Abstract: Porphyrias are diseases caused by partial deficiencies of haem biosynthesis enzymes. Acute porphyrias are characterized by a neuropsychiatric syndrome with intermittent induction of hepatic ALAS1 (δ-aminolaevulinate synthase 1), the first and rate-limiting enzyme of the haem pathway. Acute porphyria attacks are usually treated by the administration of glucose; its effect is apparently related to its ability to inhibit ALAS1 by modulating insulin plasma levels. It has been shown that insulin blunts hepatocyte ALAS1 induction, by disrupting the interaction of FOXO1 (forkhead box O1) and PGC-1α (peroxisome-proliferator-activated receptor γ co-activator 1α). We evaluated the expression of ALAS1 in a murine model of diabetes and determined the effects of the insulinomimetic vanadate on the enzyme regulation to evaluate its potential for the treatment of acute porphyria attacks. Both ALAS1 mRNA and protein content were induced in diabetic animals, accompanied by decreased Akt phosphorylation and increased nuclear FOXO1, PGC-1α and FOXO1–PGC-1α complex levels. Vanadate reversed ALAS1 induction, with a concomitant PI3K (phosphoinositide 3-kinase)/Akt pathway activation and subsequent reduction of nuclear FOXO1, PGC-1α and FOXO1–PGC-1α complex levels. These findings support the notion that the FOXO1–PGC-1α complex is involved in the control of ALAS1 expression and suggest further that a vanadate-based therapy could be beneficial for the treatment of acute porphyria attacks.
TL;DR: The calcium vanadate nanorod-modified glassy carbon electrode exhibits good performance for the electrochemical detection of tartaric acid with a detection limit of 2.4 μM and linear range of 0.005-2 mM as mentioned in this paper.
Abstract: Calcium vanadate nanorods with Ca10V6O25 phase have been synthesized by a hydrothermal process without any surfactants. Hydrothermal temperature, reaction time and calcium (Ca) raw materials play important roles in the formation and size of the calcium vanadate nanorods. The nucleation and crystal growth combined with crystal splitting process have been proposed to explain the formation and growth of calcium vanadate nanorods. The calcium vanadate nanorods are used as glassy carbon electrode-modified materials to analyze the electrochemical behaviors of tartaric acid. The calcium vanadate nanorod-modified glassy carbon electrode exhibits good performance for the electrochemical detection of tartaric acid with a detection limit of 2.4 μM and linear range of 0.005–2 mM. The analytical performance and straightforward fabrication method make the calcium vanadate nanorods promising for the development of electrochemical sensors for tartaric acid.
TL;DR: Six of the FHM2 mutations markedly affect the maximal rate of phosphorylation from ATP leading to inhibition by intracellular K+, thereby likely compromising pump function under physiological conditions.
TL;DR: In this paper, the as-prepared calcium vanadate nanorods are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), TEM, and infrared and photoluminescence (PL) spectroscopy.
Abstract: Calcium vanadate nanorods with sheaf-shaped structures have been synthesized by a facile hydrothermal route using calcium acetate and sodium orthovanadate as the raw materials. The as-prepared calcium vanadate nanorods are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and infrared and photoluminescence (PL) spectroscopy. Calcium vanadate nanorods exhibit single crystalline structure and XRD confirms the crystal structure to be hexagonal Ca10V6O25 phase. The average diameter and length of the calcium vanadate nanorods are about 50 nm and 3 μm, respectively. A possible formation process of the nanorods has been elucidated.
TL;DR: In this paper, PO4-doped BiVO4 is prepared by urea-precipitation method from nitric acid solutions of bismuth nitrate, ammonium vanadate, sodium phosphate, and urea (90 °C, 24 h).
Abstract: PO4-doped BiVO4 is prepared by the urea-precipitation method from nitric acid solutions of bismuth nitrate, ammonium vanadate, sodium phosphate, and urea (90 °C, 24 h).
TL;DR: In this article, the redox behavior of vanadate ions in alkaline solutions with NaOH concentration ranging from 0.1 M to 1 M was studied with cyclic voltammetry results.
TL;DR: In this paper, the effect of adding sodium orthovanadate (Na 3 VO 4 ) embedded in a modified zinc phosphate coating with Mn-Mg additives was investigated at different pH and vanadate concentration.
TL;DR: The results of these studies reported here show that the absence of Mg(2+) results in migration of inorganic phosphate from βA158 to a more medial position in the P-loop binding pocket, thereby disrupting essential placement and orientation of the P(i) needed to form the transition state structure and therefore MgATP.
Abstract: The mitochondrial ATP synthase (F(o)F(1)) is one of the most abundant, important, and complex enzymes found in animals and humans. In earlier studies, we used the photosensitive phosphate analogue vanadate (V(i)) to study the enzyme's mechanism in the transition state. Significantly, these studies showed that Mg(2+) plays an important role in transition state formation during ATP synthesis. Additionally, in both MgADP·V(i)-F(1) and MgV(i)-F(1) complexes, photoactivation of orthovanadate (V(i)) induced cleavage at the third residue within the P-loop (GGAGVGKT), i.e., βA158, suggesting its proximity to the γ-phosphate during transition state formation. However, despite our recent release of the F(1)-ATPase structure containing V(i), the structural details regarding the role of Mg(2+) have remained elusive. Therefore, in this study, we sought to improve our understanding of the essential role of Mg(2+) during transition state formation. We utilized Protein Data Bank structural data representing different conformational intermediates of key steps in ATP synthesis to assemble a database of positional relationships between landmark residues of the catalytic site and the bound ligand. Applying novel bioinformatics methods, we combined the resulting interatomic spatial data with an animated model of the catalytic site to visualize the exact nature of the changes in these positional relationships during ATP synthesis. The results of these studies reported here show that the absence of Mg(2+) results in migration of inorganic phosphate (P(i)) from βA158 to a more medial position in the P-loop binding pocket, thereby disrupting essential placement and orientation of the P(i) needed to form the transition state structure and therefore MgATP.
TL;DR: An antimony containing α-Keggin type acidic polyoxometalate, H4PSbMo11O40, was prepared by reacting NaMoO4, H3PO4 and Sb2O3 in the presence of aqua regia to appraise its reactivity compared to the well known vanadate analog H4PVMo11O41 as discussed by the authors.
Abstract: An antimony(V) containing α-Keggin type acidic polyoxometalate, H4PSbMo11O40, was prepared by reacting NaMoO4, H3PO4 and Sb2O3 in the presence of aqua regia to appraise its reactivity compared to the well known vanadate analog, H4PVMo11O40. Characterization was by X-ray diffraction, MALDI-TOF MS, IR, UV–vis and 31P NMR spectroscopy. Catalytic redox reactions, such as oxidative dehydrogenation using O2 and N2O as terminal oxidants were studied and showed very different reactivity of H4PSbMo11O40 versus H4PVMo11O40. It was found by DFT calculations that in contrast to analogous H4PVMo11O40 where vanadium centered catalysis is observed, in H4PSbMo11O40 catalysis is molybdenum and not antimony centered.
Journal Article•
TL;DR: In this article, Bismuth vanadate (BiVO4) powder was prepared by the sol-gel method and the phase of BiVO4 powder was studied by X-ray diffraction (XRD).
Abstract: Bismuth vanadate (BiVO4) powder was prepared by the sol-gel method. Bismuth nitrate and ammonium vanadate were used as the starting precursors with mole ratio of 1:1 in ethanol at 70°C for 1 hour. The obtained sol was changed to the yellow gel after addition of deionized water and acetic acid. The yellow gel was dried at 100°C for 48 h and calcined at 400-600°C for 2 hours. The phase of BiVO4 powder was studied by X-ray diffraction (XRD). The morphology of BiVO4 powder was investigated by scanning electron microscopy (SEM). The element composition of BiVO4 powder was indicated by energy dispersive X-ray spectrometry (EDS).
TL;DR: In this paper, the highest power neodymium-doped mixed vanadate laser oscillator is presented, using a crystal of Nd:Gd0.6Y0.4VO4 in the bounce geometry, average output powers of 27.5 W in multimode and 23 W in TEM00 operation.
Abstract: The highest power neodymium-doped mixed vanadate laser oscillator is presented. Using a crystal of Nd:Gd0.6Y0.4VO4 in the bounce geometry, average output powers of 27.5 W in multimode and 23 W in TEM00 operation were achieved. The first nonlinear mirror mode-locked operation of a mixed vanadate laser is also presented, with 16.8 W output power—the highest power mode-locked mixed vanadate oscillator, to the best of our knowledge. Self-starting continuous-wave mode locking was observed at a repetition rate of 100 MHz, pulse duration of 12.7 ps and central wavelength of 1063.8 nm, in TEM00 mode.
Patent•
04 Jul 2012
TL;DR: The vanadate garnet type fluorescent material comprises the components: A(2-2x)K(1+x)NxM2V3O12 as discussed by the authors, wherein x is more than or equal to 0 and less than equal to 1, and N is selected from at least one element of Ce, Pr, Sm, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm and Bi.
Abstract: The invention relates to a vanadate garnet type fluorescent material as well as a preparation method and the application thereof, belonging to the field of vanadate inorganic luminescent materials and aiming at solving the technical problem of providing a wideband-emission fluorescent material with wide excitation spectrum range and high luminescent strength The vanadate garnet type fluorescent material comprises the components: A(2-2x)K(1+x)NxM2V3O12, wherein x is more than or equal to 0 and less than or equal to 01, A is selected from at least one of Ca, Sr and Ba, M is selected from at least one element of Mg and Zn, and N is selected from at least one element of Ce, Pr, Sm, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm and Bi The fluorescent material belongs to a garnet-type structure in a cubic system and has high luminescent strength and wide excitation spectrum band, and an emission spectrum is emitted by a wideband for covering the whole visible light region The invention can be widely used in systems of electron, information, traffic, energy sources and illumination and has more remarkable superiority in the application of fourth-generation solid luminescent devices excited by purple light or long-wave ultraviolet light emitted by purple light or ultraviolet light-emitting diodes