12436-25-8Relevant articles and documents
Crystal structures and electronic properties in the crossover region between the spin-gap system CaV2O5 and the linear-chain system NaV2O5
Onoda, Masashige,Kagami, Takeo
, p. 3475 - 3488 (1999)
The structural and electronic properties of the Ca1-xNaxV2O5 system, where the composition CaV2O5 exhibits an isolated dimer-like spin-gap state, and NaV2O5 indicates a linear-chain magnetic behaviour and undergoes a spin-singlet transition at Tc = 34 K, have been explored by means of x-ray four-circle diffraction and through magnetization and electron paramagnetic resonance measurements. The crystal structures with 0 2O5, where the space group is Pmmn. The effective V valence is correlated with the V-O bond length in the VO5 pyramid, and the transfer integral for the next-nearest-neighbour V-V path is suggested to be larger than those for other paths, which may be consistent with the formation mechanisms of the dimer in the Ca-rich compounds and the V-O-V molecular orbital in the Na-rich compounds. The magnetic properties for 0 a large reduction of the exchange coupling constant disappears, and no magnetic ordering takes place. The characteristic spin dynamics for the Na-rich compounds is also discussed.
High-pressure synthesis, crystal structures, and characterization of CdVO3-δ and solid solutions CdVO3-NaVO3
Belik, Alexei A.,Takayama-Muromachi, Eiji
, p. 1650 - 1658 (2006)
CdVO3-δ and solid solutions of Cd1-xNaxVO3 with the GdFeO3-type perovskite structure were prepared using a high-pressure (6 GPa) and high-temperature technique. No significant oxygen and cation deficiency was found in CdVO3. Cd1-xNaxVO3 are formed in the compositional range of 0 {less-than or slanted equal to} x {less-than or slanted equal to} 0.2. CdVO3 and Cd1-xNaxVO3 demonstrate metallic conductivity and Pauli paramagnetism between 2 and 300 K. A large electronic contribution to the specific heat ( γ = 13.4 and 11.2 mJ / ( mol K2) for CdVO3 and Cd0.8Na0.2VO3, respectively) was observed at low temperatures due to the strongly correlated electrons. Crystal structures of CdVO3 and Cd0.8Na0.2VO3 were refined by X-ray powder diffraction: space group Pnma; Z = 4; a = 5.33435 ( 7 ) A, b = 7.52320 ( 9 ) A, and c = 5.26394 ( 6 ) A for CdVO3 and a = 5.32056 ( 9 ) A, b = 7.50289 ( 13 ) A, and c = 5.25902 ( 8 ) A for Cd0.8Na0.2VO3.
Bovine serum albumin binding, antioxidant and anticancer properties of an oxidovanadium(IV) complex with luteolin
Naso, Luciana G.,Lezama, Luis,Valcarcel, María,Salado, Clarisa,Villacé, Patricia,Kortazar, Danel,Ferrer, Evelina G.,Williams, Patricia A.M.
, p. 80 - 93 (2016)
Chemotherapy using metal coordination compounds for cancer treatment is the work of the ongoing research. Continuing our research on the improvement of the anticancer activity of natural flavonoids by metal complexation, a coordination compound of the natural antioxidant flavone luteolin (lut) and the oxidovanadium(IV) cation has been synthesized and characterized. Using different physicochemical measurements some structural aspects of [VO(lut)(H2O)2]Na·3H2O (VOlut) were determined. The metal coordinated to two cis-deprotonated oxygen atoms (ArO-) of the ligand and two H2O molecules. Magnetic measurements in solid state indicated the presence of an effective exchange pathway between adjacent vanadium ions. VOlut improved the antioxidant capacity of luteolin only against hydroxyl radical. The antitumoral effects were evaluated on MDAMB231 breast cancer and A549 lung cancer cell lines. VOlut exhibited higher viability inhibition (IC50 = 17 μM) than the ligand on MDAMB231 cells but they have the same behavior on A549 cells (ca. IC50 = 60 μM). At least oxidative stress processes were active during cancer cell-killing. When metals chelated through the carbonyl group and one adjacent OH group of the flavonoid an effective improvement of the biological properties has been observed. In VOlut the different coordination may be the cause of the small improvement of some of the tested properties of the flavonoid. Luteolin and VOlut could be distributed and transported in vivo. Luteolin interacted in the microenvironment of the tryptophan group of the serum binding protein, BSA, by means of electrostatic forces and its complex bind the protein by H bonding and van der Waals interactions.
Phase equilibria in the V2O5-NaVO3- Ca(VO3)2-Mn2V2O7 system and interactions of phases with H2SO4 and NaOH solutions
Krasnenko,Sirina,Rotermel'
, p. 1489 - 1494 (2008)
Phase composition of the V2O5-NaVO 3-Ca(VO3)2-Mn2V2O 7 system was studied, and a subsolidus phase diagram constructed. The tetrahedration of the diagram is determined by the fact that the end-member of Ca1-x Mn x (VO3)2 solid solution is in equilibrium with all compounds of the system (V2O5, NaVO3, Ca(VO3)2), vanadium β-bronzes Na x V2O5 (0.22 ≤ x ≤ 0.40) and κ-bronzes (0.25 ≤ x ≤ 0.45, 0 ≤ y ≤ 0.16), Mn 2V2O7, and Na2Mn3(V 2O7)2 and with the end-members of reciprocal solid solutions based on calcium and sodium metavanadates. At 20°C, the degree of vanadium dissolution α for Na2Ca(VO3) 4 is 100% for 0.5 ≤ pH ≤ 10; for the other phases of the system, vanadium dissolution ranges from 100 to 10% for pH below 3.5; in the alkaline pH range, ≤ 10%. Sodium for calcium substitution in Ca(VO 3)2 increases α in aqueous NaOH to 20%. For Na 2Mn3(V2O7)2, α decreases from 92 to 80% as pH changes from 0.5 to 2.5; at pH above 4, α = 30%.
High-performance NaVO3 with mixed cationic and anionic redox reactions for Na-ion battery applications
Su, Bizhe,Wu, Shuilin,Liang, Hanqin,Zhou, Wenchong,Liu, Junnan,Goonetilleke, Damian,Sharma, Neeraj,Sit, Patrick H.-L.,Zhang, Wenjun,Yu, Denis Y.W.
, p. 8836 - 8844 (2020)
Sodium-ion batteries (NIBs) are a potential low-cost alternative to lithium-ion batteries for large-scale energy storage, but many high-capacity NIB cathode materials undergo irreversible structural changes during charge and discharge, leading to fast capacity fading. Herein, monoclinic NaVO3 exhibits good cycle performance with high capacity as a cathode material for NIBs. In situ synchrotron X-ray diffraction studies show that the material structure is virtually invariant during Na+ (de)intercalation, with the a and b lattice parameters changing only by 0.13 and 0.19%, respectively. The material undergoes an oxygen redox reaction during initial charge while delivering a remarkable specific capacity of 245 mAh g-1 (1.2-4.7 V) with contributions from cationic (V4+/V5+) and anionic (O2-/O-) redox couples during discharge. The stable VO4 tetrahedral framework also enables the material to give superior rate and cycle capabilities, with a capacity of 164 mAh g-1 (67% utilization) at a current of 1000 mA g-1 (about 5C) and a capacity retention of 90% after 50 cycles. Density functional theory calculations further verify the stability of the material and the charge-discharge mechanism. This work can broaden the horizon for designing high-energy cathode materials with enhanced structural stability for sodium-ion batteries.
Amorphous sodium vanadate Na1.5 + yVO3, a promising matrix for reversible sodium intercalation
Venkatesh,Pralong,Lebedev,Caignaert,Bazin,Raveau
, p. 100 - 102 (2014)
Sodium insertion into the vanadate NaVO3 shows the formation of an amorphous phase with the composition Na1.5 + yVO3. The latter phase exhibits reversible electrochemical sodium intercalation/de- intercalation properties through a solid solution-like process, for 0 +/Na and a capacity of 150 mAh/g. This result opens the route to the investigation of amorphous matrices involving transition metal oxides for sodium ion battery applications.
Chemical sodiation of V2O5by Na2S
Haberkorn, Robert,Bauer, Jessica,Kickelbick, Guido
, p. 3197 - 3202 (2014)
Chemical sodiation of V2O5 at low temperatures allows to synthesize NaxV2O5 with 0≤ x≤ 1, while classic high temperature syntheses yield in either x≤ 0.02 (α-phase) or 0.7≤ x (α′-phase), or other phases (β-phase, δ-phase) or mixtures thereof. A suspension of V2O5 in acetonitrile and Na2S as sodiation agent were used. The maximum amount of sodiation was obtained by using an excess of Na2S, refluxing the acetonitrile during the reaction, and precedent ball milling of the V2O5. If only low amounts of Na2S were used as starting material, a mixture of fractions of NaxV2O5with different values of x was obtained. All these fractions belong to the α- or α′-phase, space group Pmmn.
High pressure behavior of α-NaVO3: A Raman scattering study
Rao, Rekha,Sakuntala,Shaikh,Deb
, p. 2824 - 2829 (2007)
The reported pressure-induced amorphization in α-NaVO3 has been re-investigated using Raman spectroscopy. Discontinuous changes are noted in the Raman spectrum above 5.6 GPa implying large structural changes across the transition. The decrease in frequency of the V-O stretching mode across the transition suggests that the vanadium atom may be in octahedral coordination in the high pressure phase. Excessive broadening of the internal modes is observed above 6 GPa. New peaks characteristic of a crystalline phase gain in intensity at higher pressures in the bending modes region; however, the transformation is not complete even at 13 GPa. Co-existence of phases is noted over a significant pressure range above the onset of transition. Pressure released spectrum is found to be a mixture of crystalline α-phase, traces of crystalline β-phase and highly disordered phase consisting of V-O units in five- and six-fold coordination.
THE INFRARED AND RAMAN SPECTRA OF MATRIX-ISOLATED M-V-O SYSTEMS. THE CHARACTERIZATION OF MVO3 AND MVO2 MOLECULES
Bencivenni, L.,Gingerich, K. A.
, p. 197 - 202 (1983)
Gaseous alkali vanadates MVO3 and MVO2 have been identified by means of IR matrix isolation spectroscopy and their spectra interpreted on the basis of C2v ring structures.Raman spectra have been obtained for matrix-isolated CsVO3 and CsVO2.The
Magnetic Susceptibility of Quasi-One-Dimensional Compound α'-NaV2O5 - Possible Spin-Peierls Compound with High Critical Temperature of 34 K -
Isobe, Masahiko,Ueda, Yutaka
, p. 1178 - 1181 (1996)
Stoichiometric powder samples of α'-NaV2O5 were synthesized and the magnetic susceptibility was measured in the temperature range from 2K to 7000 K. The magnetic susceptibility has a good fit to the equation for an S = 1/2 antiferromagnetic Heisenberg linear chain with J/KB = 280 K and g = 2 above 34 K. Below 34 K the magnetic susceptibility rapidly decreases with decreasing temperature to a constant value of 1.49 × 10-4 emu/V4+ -mol which is reasonable for spin-singlet V4+-V4+ pairs. This rapid reduction of the spin susceptibility below 34 K suggests the existence of a spin-Peierls transition. α'-NaV2O5 is a possible spin-Peierls compound with the highest critical temperature yet observed.
