The Sodium Tungsten Bronzes<sup>1,2</sup>

Brown, B. W.; Banks, E.

doi:10.1021/ja01633a004

Cited by 211 publications

(134 citation statements)

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“…In calculations involving supercells of tungsten trioxide the distortions are seen [20]. Tungsten bronzes on the other hand do form the simple cubic structure at high intercalation levels [29]. The hexagonal structure, which was also studied for comparison, is the same for both the oxide and bronzes.…”

Section: Structurementioning

confidence: 97%

Density-functional studies of tungsten trioxide, tungsten bronzes, and related systems

Ingham

Hendy

Chong³

et al. 2005

Phys. Rev. B

115

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Tungsten trioxide adopts a variety of structures which can be intercalated with charged species to alter the electronic properties, thus forming 'tungsten bronzes'. Similar optical effects are observed upon removing oxygen from WO3, although the electronic properties are slightly different. Here we present a computational study of cubic and hexagonal alkali bronzes and examine the effects on cell size and band structure as the size of the intercalated ion is increased. With the exception of hydrogen (which is predicted to be unstable as an intercalate), the behaviour of the bronzes are relatively consistent. NaWO3 is the most stable of the cubic systems, although in the hexagonal system the larger ions are more stable. The band structures are identical, with the intercalated atom donating its single electron to the tungsten 5d valence band. Next, this was extended to a study of fractional doping in the NaxWO3 system (0 ≤ x ≤ 1). A linear variation in cell parameter, and a systematic change in the position of the Fermi level up into the valence band was observed with increasing x. In the underdoped WO3−x system however, the Fermi level undergoes a sudden jump into the conduction band at around x = 0.2. Lastly, three compounds of a layered WO4 · α,ω-diaminoalkane hybrid series were studied and found to be insulating, with features in the band structure similar to those of the parent WO3 compound which relate well to experimental UVvisible spectroscopy results.

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Section: Structurementioning

confidence: 97%

Density-functional studies of tungsten trioxide, tungsten bronzes, and related systems

Ingham

Hendy

Chong³

et al. 2005

Phys. Rev. B

115

View full text Add to dashboard Cite

show abstract

“…In this laboratory, it is the method of choice for the determination of tungsten. A detailed discussion of hydrogen reductions is given in Chapter V. Any of the alkali metals can be determined gravimetrically as the sulfate (18). One should understand that these methods probably cannot be applied if a fusion has been employed to decompose the sample.…”

Section: B Prior Analytical Chemistry Of the Alkali Metal Tungsten Bmentioning

confidence: 99%

“…If an alkali metal chloride is one of the decomposition products, one can precipitate or titrate the chloride with silver (18).…”

Section: B Prior Analytical Chemistry Of the Alkali Metal Tungsten Bmentioning

confidence: 99%

“…One non-destructive analysis for alkali metals is the x-ray method of Brown and Banks (18). So far, it has been possible to apply this method to cubic bronzes only.…”

Section: B Prior Analytical Chemistry Of the Alkali Metal Tungsten Bmentioning

confidence: 99%

“…All methods so far applied to the determination of tungsten have been gravimetric. Tungsten has been converted to tungstate, which was then precipitated by tannin-cinchonine (12, 31)» cinchonine alone (17), cinchonine-nitric acid (32), nitric acid (18,121,122), mercury(I) (77), or mercury(II) (127).…”

Section: Determination Of the Tungstenmentioning

confidence: 99%

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