Vanadates strontium

Simner SP, Hardy JS, Stevenson JW, and Armstrong TR. Sintering of lanthanum chromite using strontium vanadate. Solid State Ionics 2000 128 53-63. 

Strontium vanadates. Authors [85] studied mechanochemical synthesis of SrVOs with perovskite structure. Initial mixtures comprising Sr(OH)2 with V2O5, VO2 or V2O3 were milled in a multi-ring type mill (MICROS MIC-0) at 2(XX) rpm for 60 min in air or N2-4% H2 and then heated at 800 C for 10 h. Single phase SrV03 was obtained by firing of... 

H. 8-Hydroxyquinaldine (XI). The reactions of 8-hydroxyquinaldine are, in general, similar to 8-hydroxyquinoline described under (C) above, but unlike the latter it does not produce an insoluble complex with aluminium. In acetic acid-acetate solution precipitates are formed with bismuth, cadmium, copper, iron(II) and iron(III), chromium, manganese, nickel, silver, zinc, titanium (Ti02 + ), molybdate, tungstate, and vanadate. The same ions are precipitated in ammoniacal solution with the exception of molybdate, tungstate, and vanadate, but with the addition of lead, calcium, strontium, and magnesium aluminium is not precipitated, but tartrate must be added to prevent the separation of aluminium hydroxide. 

Cheng Z, Zha S, Aguilar L, and Liu M. Chemical, electrical, and thermal properties of strontium doped lanthanum vanadate. Solid State Ionics 2005 176 1921-1928. 

Vanadates For the isostructural strontium and barium ortho-vanadates the V-—0 vibrational frequencies decrease with increasing effective nuclear charge [51]. Similar orthovanadates with the apatite structure have for a given halogen ion decreasing frequencies of the VO4 ion in the order Ca>Sr >Ba ((62) and Table 4]. However, it is impossible to see any trend towards the tiivalent lanthanide cations (59). The IR bands are so wide in this case that small changes cannot be measured. 

The synthesis of the title compositions has been selected as representative of compounds that can readily be prepared by the flux-reaction technique. In this technique, a halide melt serves both as a flux and as a constituent component of the basic reaction. The procedure has been described in the literature1 and has served for the preparation of a variety of ternary oxides, usually in the form of small, well-defined, single crystals. The halide phosphates and vanadates of strontium represent the apatite and spodiosite structures, both interesting compositions from a biochemical and solid-state point of view. 

The Srs(P04)3Cl crystals are hexagonal needles with lattice parameters ah = 9.953 A. and ch = 7.194 A. The needle axis corresponds to the crystallographic c axis. The europium(II) doped sample is a phosphor, readily excitable with electrons, x-rays, and both short and long ultraviolet light. It emits in the blue with a peak at 445 nm. Crystals of strontium chloride vanadate(V) are orthorhombic platelets with lattice constants a = 7.43 A., b = 11.36 A., and c = 6.54 A., with the b axis corresponding to the thin dimension of the flakes. Strontium chloride vanadate(V) is a self-activated phosphor giving broadband emission with a peak at 423 nm. when excited with 2537-A. radiation. All compounds are insulators, with resistivities >1012 ft-cm. 

It has been seen in the previous section that the ratio of the onsite electron-electron Coulomb repulsion and the one-electron bandwidth is a critical parameter. The Mott-Hubbard insulating state is observed when U > W, that is, with narrow-band systems like transition metal compounds. Disorder is another condition that localizes charge carriers. In crystalline solids, there are several possible types of disorder. One kind arises from the random placement of impurity atoms in lattice sites or interstitial sites. The term Anderson localization is applied to systems in which the charge carriers are localized by this type of disorder. Anderson localization is important in a wide range of materials, from phosphorus-doped silicon to the perovskite oxide strontium-doped lanthanum vanadate, Lai cSr t V03. 

Compounds that have been proposed to react by this mechanism include barium titanate, calcium titanate, calcium carbonate, strontium titanate and magnesium oxides[8,9,10]. All these basic compounds should theoretically react with vanadic acid and bind it in the trap and have proved effective in laboratory evaluations. However, sulfur competition negatively affects the performance of these traps in commercial units[8,l 1],... 

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