Crystal Structure of α-VPO<sub>5</sub>

Jordan, Byron D.; Calvo, C.

doi:10.1139/v73-396

Cited by 146 publications

(63 citation statements)

References 3 publications

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“…Several different polymorph of the oxidized VOPO 4 have been reported in the literature: [5][6][7][8] ␣ I -VOPO 4 , ␣ II -VOPO 4 , ␤-VOPO 4 , ␥-VOPO 4 , ␦-VOPO 4 , ⑀-VOPO 4 , and -VOPO 4 . During thermal treatment at high temperature the consecutive transitions ␣ I → ␣ II → ␤-VOPO 4 or ␦ → ␥ → ␤-VOPO 4 have been observed.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure ofβ−VOPO4

Willinger

Schlögl

2005

Phys. Rev. B

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Vanadium phosphorus oxides are used as catalysts in the selective oxidation of n-butane to maleic anhydride. The working catalyst comprises besides the main pyrophosphate phase in which the vanadium is in a 4+ oxidation state also a, predominantly preparation dependent, amount of different pentavalent vanadylorthophosphate phases. In order to elucidate the role of the pentavalent phases it is necessary to investigate them in detail. The present work reports the synthesis, characterization and a detailed investigation of the electronic structure of bulk ␤-VOPO 4 in company with simulated and experimental core-shell excitation spectra.

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Section: Introductionmentioning

confidence: 99%

Electronic structure ofβ−VOPO4

Willinger

Schlögl

2005

Phys. Rev. B

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“…The data, corrected for Lorentz-polarization and absorption, were used together with the parameters of disordered ~-VPO5 (Jordan & Calvo, 1973)to refine the structure. Convergence of the least-squares refinement yielded an R of 0.12 with residual peaks in the difference Fourier map that indicated that the compound was non-stoichiometric.…”

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confidence: 99%

α-V1.08P0.92O5 at 22°C

Jordan¹,

Calvo²

1976

Acta Crystallogr Sect B

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Abstract. oc-Vl.os(1)Po.9205, tetragonal, P4/n; a = 6.011 (4), c=4.452 (4) A; Z=2, Dealt=3"39 gcm -3, 147 independent reflexions. The structure was refined by full-matrix least-squares methods, R=0.076, with scintillation counter-measured intensities and monochromatized Mo K~ radiation. The composition was determined by varying the occupancy of the tetrahedral site. The vanadyl bond length is 1.578 (9) /k. Unlike stoichiometric 0c-VPO5 no evidence of positional disorder was found.Introduction. Crystals were grown in a Pt crucible in an attempt to produce large single crystals by the Czochralski procedure. The present crystals grew at the interface with the crucible and at the surface of the charge. Crystals offl-VPO5 and some as yet unidentified crystals were found near the centre of the crucible.A crystal with dimensions 0.5 × 0.5 × 0.05 mm was used for data collection with a Syntex P] diffractometer. The data, corrected for Lorentz-polarization and absorption, were used together with the parameters of disordered ~-VPO5 (Jordan & Calvo, 1973)to refine the structure. Convergence of the least-squares refinement yielded an R of 0.12 with residual peaks in the difference Fourier map that indicated that the compound was non-stoichiometric. Subsequent refinements, with weights set as w-1 = 0.9 + 0.20F+ 0.005F 2, and with the extinction parameter varied indicated that 8 (1)% of the tetrahedral sites were occupied by V.

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“…In Fig. 2 Li 2 VGeO 5 has a structure very similar to ␣-VOPO 4 [11,12]. The layered units are isostructural except that the two interlayer Li + ions charge compensate for the V(IV) in our title compound.…”

Section: Resultsmentioning

confidence: 79%