Thermic investigations of hexagonal hydrogen bronze, HxWO3

Šušić, M.V.; Solonin, Yuriy

doi:10.1007/bf01174064

Cited by 20 publications

(8 citation statements)

References 9 publications

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“…Figure shows excerpts of X-ray diffraction patterns of m-WO 3 used as an initial product, the intermediate h-WO 3 phase, and the nonstoichiometric WO 3 - x phase derived due to hydrogen reduction of h-WO 3 . The h-WO 3 phase was derived from copper tungstate, CuWO 4 , with subsequent copper dissolution in HNO 3 and following oxidation of the H 0.24 WO 3 phase, as mentioned in the Experimental Section (for detailed information see refs and ). As can be seen from Figure , the studied h-WO 3 specimen was mainly a single-phase material and contained small amounts of m-WO 3 .…”

Section: Resultsmentioning

confidence: 99%

“…Copper tungstate, CuWO 4 , was used as a precursor for obtaining both the stoichiometric and nonstoichiometric hexagonal tungsten trioxides studied in the present work. The precursor was obtained by a solid-state reaction of CuO and the usual monoclinic form of tungsten trioxide, m-WO 3 , according to the relation CuO + WO 3 = CuWO 4 . , The solid-state reaction was carried out in air at 800 °C. The reduction of CuWO 4 was performed in hydrogen at 300 °C.…”

Section: Methodsmentioning

confidence: 99%

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Nonstoichiometric Tungsten Oxide Based on Hexagonal WO₃

Solonin

Khyzhun

Graivoronskaya

2001

Crystal Growth & Design

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On the initial stage of reduction of hexagonal tungsten trioxide, h-WO 3 , the nonstoichiometric h-WO 2.8 phase was synthesized. The X-ray powder diffraction analysis and subsequent refinement using the Rietveld Full Profile Matching & Integrated Intensities Refinement of X-ray and/or Neutron Data Programs (FullProf Version 3.5 Dec97-LLB-JRC) indicate that the crystal structure of the h-WO 2.8 phase is ascribed to the UO 3 structure type with lattice parameters a ) 0.3625 nm and c ) 0.3780 nm. The X-ray photoelectron spectroscopy (XPS) method was applied to study the electronic structure of the nonstoichiometric tungsten trioxide. The XPS valence band and core-level spectra of the h-WO 2.8 phase and, for comparison, h-WO 3 were derived. The formation of an additional near-Fermi subband, which is absent on the XPS valence-band spectrum of hexagonal tungsten trioxide, was observed on the spectrum of the nonstoichiometric hexagonal WO 2.8 compound. Half-widths of the XPS valence band as well as both W 4f and O 1s core-level spectra increase somewhat when going from h-WO 3 to h-WO 2.8 .

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Nonstoichiometric Tungsten Oxide Based on Hexagonal WO₃

Solonin

Khyzhun

Graivoronskaya

2001

Crystal Growth & Design

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“…Copper tungstate, CuWO 4 , studied in the present paper was obtained by solid state reaction of CuO and the usual monoclinic form of tungsten trioxide, m-WO 3 , according to the relation CuO + WO 3 = CuWO 4 [7,8]. The solid-state reaction was carried out on air at 800 • C [15].…”

Section: Methodsmentioning

confidence: 99%

“…As shown in Refs. [7,8], copper tungstate, CuWO 4 , is also a very prospective precursor for synthesis of the hexagonal form of tungsten trioxide. A product derived during reduction of CuWO 4 in flowing hydrogen at 300 • C with following treatment by concentrated HNO 3 upto the full desolving of copper leads to the formation of a brown-blue hexagonal hydrogen tungsten bronze, H x WO 3 , with x = 0.24 [9].…”

Section: Introductionmentioning

confidence: 99%

Electronic structure of CuWO4: XPS, XES and NEXAFS studies

Khyzhun

Strunskus

Cramm

et al. 2005

Journal of Alloys and Compounds

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“…The study of hydrogen bronze materials (e.g., H x WO 3 and H x MoO 3 ) has been of interest since the early 1970s. − Hydrogen molybdenum bronze, as a potential hydrogenation, dehydration, and reduction catalyst, has received extensive attention. It can be prepared effectively via hydrogen spillover in the presence of Pt or Pd catalyst.…”

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confidence: 99%