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Showing papers on "Vanadate published in 1977"


Journal ArticleDOI
TL;DR: A potent (Na,K)-ATPase inhibitor purified from "Sigma Grade* ATP" has been identified as vanadium using electron probe microanalysis and confirmed by microwave-induced emission spectroscopy and electron paramagnetic resonanceSpectroscopy.

815 citations



Journal ArticleDOI
TL;DR: The ferroelectric Curie temperature, Tc = 1383 K, has been determined from dielectric, thermal and pyroelectric studies as discussed by the authors, and large transparent crystals have been grown by Czochralski pulling.
Abstract: Ferroelectricity has been discovered in calcium vanadate. Large, transparent crystals have been grown by Czochralski pulling. Electrical 180° domains of millimeter dimensions are observed by etching as-grown crystals. The ferroelectric Curie temperature, Tc = 1383 K, has been determined from dielectric, thermal and pyroelectric studies.

69 citations



Journal ArticleDOI
TL;DR: In this article, the chemistry of vanadium in solution has been investigated over the entire pH range, with special emphasis on rare earth precipitates, and it was shown that vanadium appears to be oxidized early in the titration to form VO 2 + ion which then condenses in solution to form vanadate anionic precipitates.

30 citations


Journal ArticleDOI
A. Paul1, N. Yee1
TL;DR: The vanadium(V)/vanadium(IV) ratio in the melt increased with increasing partial pressure of oxygen, lowering temperature of melting, and with increasing total vanadium content of the melt.
Abstract: The vanadium(IV)-vanadium(V) equilibrium in a 37.5BaO, 5.0Al 2 O 3 , 57.5B 2 O3 mol% + X mol% V 2 O 5 (where X = 0.25−32.5) glass system has been studied as functions of temperature, partial pressure of oxygen and total vanadium concentration of the melt. The vanadium(V)/vanadium(IV) ratio in the melt increased with increasing partial pressure of oxygen, lowering temperature of melting, and with increasing total vanadium content of the melt. With X ⩾ 10, the vanadium(V)/vanadium(IV) ratio became almost independent of the total vanadium content of the melt. With this knowledge of oxidation-reduction behaviour, a series of glasses containing 2.8−32.5 mol% V 2 O 5 (at about 4 mol% intervals) and having a constant vanadium(IV)/vanadium(V) ratio (0.17) were prepared. Density, electronic absorption spectrum (both d-d and charge transfer transitions), and ESR of these glasses were measured. Optical and ESR spectra of these glasses indicated the vanadium(IV) to be present as vanadyl ion, VO 2+ ; g | decreased monotonically with increasing vanadium content of these glasses, whereas g β remained unchanged. The charge transfer transition energy due to vanadium(V) decreased, and the extinction coefficient increased by orders of magnitude with increasing vanadium content of the glass; the most striking changes occurred at X ≈ 10 mol%. DC conductivity of these glasses was measured at different temperatures; a plot of log ( ϱ / T ) versus 1/ T produced straight lines. The slope of these lines remained almost constant (39 ± 1 kcal/mol) for the glasses containing up to about 10 mol% V 2 O 5 ; with further increase of V 2 O 5 the slope decreased sharply. It has been concluded that the abrupt changes in properties like partial molar volume of V 2 O 5 , charge transfer spectrum of vanadium(V), activation energy of polaron hopping — all of which occurred around X ≈ 10 mol% — is due to a major change in the nature of vanadate groups rather than vanadium(IV) in these glasses.

22 citations


Patent
09 May 1977
TL;DR: In this article, a process for the preparation of pigmentary primrose yellow bismuth vanadate is described, which is then subjected to aqueous digestion to produce pigmentary monoclinic Bismuth Vanadate.
Abstract: Process for the preparation of pigmentary primrose yellow bismuth vanadate by reacting bismuth nitrate with an alkali vanadate under controlled conditions to obtain a bismuth vanadate gel which is then subjected to aqueous digestion to produce pigmentary monoclinic bismuth vanadate.

22 citations


Patent
08 Apr 1977
TL;DR: In this article, a process for recovering vanadium values from carbonaceous type vanadium ores, and vanadium scrap, such as vanadium contaminated spent catalyst, is disclosed which comprises roasting the vanadium containing material in air at a temperature less than about 600° C to produce a material substantially devoid of organic matter, subjecting said roasted material to a further oxidizing roast in an oxygen atmosphere at at least about 800° C for a period sufficient to convert substantially all of the vananium to the soluble form, leaching the calcine with a suitable dilute mineral acid or
Abstract: A process for recovering vanadium values from carbonaceous type vanadium ores, and vanadium scrap, such as vanadium contaminated spent catalyst, is disclosed which comprises roasting the vanadium containing material in air at a temperature less than about 600° C to produce a material substantially devoid of organic matter, subjecting said roasted material to a further oxidizing roast in an oxygen atmosphere at a temperature of at least about 800° C for a period sufficient to convert substantially all of the vanadium to the soluble form, leaching the calcine with a suitable dilute mineral acid or water at a pH of neutral to about 2 to recover vanadium values, precipitating vanadium values as iron vanadate from the leach solution with a soluble iron compound at a pH from neutral to about 1, and recovering ferrovanadium from the iron vanadate by a reduction vacuum smelting operation. The conversion of vanadium in the ore to the soluble form by the oxidizing roast is accomplished without the addition of an alkaline salt during calcining.

18 citations


Patent
Richard William Hess1
09 May 1977
TL;DR: A pigmentary, bright primrose yellow monoclinic bismuth vanadate and processes for the preparation thereof were described in this article, where the mixture of Bismuth nitrate with an alkali vanadates under controlled conditions was obtained.
Abstract: A pigmentary, bright primrose yellow monoclinic bismuth vanadate and processes for the preparation thereof by reacting bismuth nitrate with an alkali vanadate under controlled conditions to obtain a bismuth vanadate gel followed by aqueous digestion or calcination to produce pigmentary, bright primrose yellow monoclinic bismuth vanadate.

17 citations


Journal ArticleDOI
01 May 1977-Talanta
TL;DR: A spectrophotometric method for determining some penicillins has been developed and has been successfully applied for the determination ofPenicillin G sodium, phenoxymethyl penicillin, ampicillin Sodium, phenethicillin potassium, cloxacillin sodium and methicillin sodium.

16 citations


Journal ArticleDOI
TL;DR: In the aluminothermic reduction of m e t a l oxide, calcium oxide is often used as a flux as discussed by the authors, and instead of forming an extraneous addition, it can sometimes be present in chemical combination with the metal oxide.
Abstract: In the aluminothermic reduction of m e t a l oxide, calcium oxide is often used as a flux. The calcium oxide instead of forming an extraneous addition can sometimes be present in chemical combination with the m e t a l oxide. A familiar example is the aluminothermic reduction of calcium tungstate for the production of ferrotungsten. It has been stated1 that good coalescence of ferrotungsten is probably due to calcium oxide being an integral part of the tungsten resource, thus being made available essentially on a molecular basis for combining with alumina reaction product and quickly forming a fluid s lag . This can be considered to be a favorable state of affairs in the aluminothermic reduction of metal oxide as tied up with calcium oxide. In this context, reference can also be drawn t o the aluminothermic reduction of calcium molybdate for the production of ferromolybdehum and of molybdenum reported previously from this laboratory.~'3 This communication is an account of the efforts made for the preparation of vanadium and of ferrovanadium from calcium vanadates. The literature has made reference to the precipitation of calcium vanadate from vanadium bearing aqueous solution.4-7 T h e r e is however no information available on any technical use that has been developed for calcium vanadate. Aluminothermic reduction of vanadium pentoxide for the production of ferrovanadium or of vanadium in the industrial practice is known to be c a r r i e d out in presence of lime serving as a flux. This points towards the possibility for calcium vanadate as an alternative starting material for the aluminothermic reduction. For use in the present investigation the calcium vanadates were prepared in the laboratory. The compounds corresponding t o 2 CaO.V205 and to 4 CaO.V2Os were precipitated from alkaline sodium vanadate colution by treatments with CaC12 and lime respectively essentially in accordance with published work.7 The precipitated vanadium salts were dried, calcined at 1123 K and ground predominantly to -100 m e s h . The 2 CaO.V~Os and the 4 CaO.V2Os compounds, as made ready for use, analyzed 59.18 pct VaO5 and 44 pct V2Os respectively. Aluminum powder (grade ' C ' , 1 2 0 mesh) as received from M/s Indian Aluminium Co. was used as the reductant. The proc e d u r e for carrying out the aluminothermic r e d u c tions in refractory lined open vessels was essentially

Patent
29 Jun 1977
TL;DR: In this paper, a catalyst mass of silver vanadate and iron vanadates was used in the vapor phase oxidative conversion of toluene to benzaldehyde and benzoic acid using oxygen or ozone and steam according to the disclosed process.
Abstract: A catalyst mass of silver vanadate and iron vanadate, optionally also including at least one rare earth metal vanadate, is used in the vapor phase oxidative conversion of toluene to benzaldehyde and/or benzoic acid using oxygen or ozone and steam according to the disclosed process. Catalyst activity and selectivity are improved.

Journal ArticleDOI
TL;DR: In this article, Stannic vanadate has been synthesized by varying the mixing ratio of the reagents and pH of the mixture, and the most stable sample was synthesised by mixing 0.25 m solutions of stanni...
Abstract: Samples of stannic vanadate have been synthesized by varying the mixing ratio of the reagents and pH of the mixture. The most stable sample has been synthesized by mixing 0.25 M solutions of stanni...


Journal ArticleDOI
TL;DR: In this paper, the dependence of the spin Hamiltonian and the splitting of the 3D level of the V(IV) ion in the field of the oxygen ligands on the composition of phosphate-vanada-te semiconducting glasses mV205 �9 (100- m) P20.V2Os" 25P205 on the concentration of V, P(V), Ca 2+, and Ba 2+, joined to V( IV) through oxygen ligand, has been examined.
Abstract: The dependence of the components of the g tensor and the HFS constant of the complex VO040 in phosphate-vanada te sere[conducting glasses of the system mV205 �9 (100-m)P205 (m = 100-2) and the nonsemiconductin g glasses 24CaO.V205. 25P205 and 24BaO.V2Os" 25P205 on the concentration of V(V), P(V), Ca 2+, and Ba 2+, joined to V(IV) through oxygen ligands, has been examined. The parameters of the spin Hamilton[an, the splitting of the 3d level (that is, themagnitude of the energy of the d-d transition) of the V(IV) ion in the field of the yl oxygen and the in-plane oxygen ligands, and the mechanism of electrical conductivity have been determined. The aim of the present work was to study the dependence of the parameters of the spin Hamiltonian (SH), the nature of the chemical bonding, the concentration of unpaired electrons, and the splitting of the energy levels of the 3d V(W) ion in the field of the oxygen ligands on the composition of phosphate-vanada te semiconducting glasses mV205 �9 (100- m) P20. 5 (I) (m = 100- 2) and the nonsemiconductia g phosphate- vanadate glasses 24 CaO" V205 "25P205 (I_D and 24BaO. V205- 25P205 (III) by ESR and electronic absorption methods. The parameters of the SH, gs gll' A-t' and AII were determined more accurately in the present work than in earlier work [1, 2]. The ESR studies were carried out on an Rt~-1301 spectrometer at 77 and 295~ The diffuse reflectance spectrum was recorded using the monochromator of an MOM-201 spectrophotomete r and a PDO-1 diffuse reflectance attachment [3].


Journal ArticleDOI
TL;DR: The vanadium(111) tris-β-diketonates derived from pentane-2,4-dione and 13 other βdiketones were prepared by reduction of oxovanadium(1V) sulphate with sodium dithionite and chelation of the vanadium with ligand in an aqueous alcohol medium.
Abstract: The vanadium(111) tris-β-diketonates derived from pentane-2,4-dione and 13 other β-diketones were prepared by reduction of oxovanadium(1V) sulphate with sodium dithionite and chelation of the vanadium(111) with ligand in an aqueous alcohol medium. The chelate prepared with pentane-2,4-dione was also obtained by reduction of ammonium vanadate and oxobis(pentane-2,4-dionato)-vanadium(1V). Preparative details are given and the advantages, and some difficulties, of the method are discussed.