Electrochemical Properties of  WO 3 · x (  H 2 O  ) : I . The Influences of Water Adsorption and Hydroxylation

Yoshiike, Nobuyuki; Kondô, Shigeo

doi:10.1149/1.2119570

Cited by 89 publications

(31 citation statements)

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“…Low coloration at these operating potentials are consistent with a displacement of the W V /W VI redox potential towards higher negative values, typical of aquated species. [17,19] As shown in Figure 6, a positive polarization at +0.4 V was sufficient to reduce absorbance to almost the initial value. However, the most important aspect was the kinetics of the process.…”

Section: Electrochromic Characterizationmentioning

confidence: 85%

“…This phenomenon is explained by the presence in the matrix of a high hydrogen content, known to accelerate the electrochemical processes in this type of material. [17,18] On the other hand, the presence of OH groups was previously shown by physical± chemical characterization of the material (X-ray photoelectron spectroscopy (XPS) analysis). Coloration±decoloration processes are fast, even after repeated cycles (not shown), but the electrochromic properties of the films appear to be progressively damaged (e.g., appearance of a residual coloration after every cycle).…”

Section: Electrochromic Characterizationmentioning

confidence: 97%

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Amorphous WO3 Films via “Wet” CVD of a WVI Oxoalkoxide Precursor

Basato¹,

Brescacin²,

Tondello³

2001

Chem. Vap. Deposition

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Amorphous WO 3 films are obtained by using the oxoalkoxide precursor WO(O t Bu) 4 . This compound is easily evaporated at 80 C, and reacts with water at the surface of the substrate (Si(100) or soda lime glass (KGlass)) to give films of tungsten oxide in a combined CVD sol±gel process. The films deposited at low temperatures (150 C, Si(100), or 100 C, KGlass) can be defined as tungstic species (of general formula WO n (OH) m ), having interesting electrochromic properties. Thermal treatment at temperatures over 400 C converts the material to a more typical WO 3 film.

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Section: Electrochromic Characterizationmentioning

confidence: 85%

Section: Electrochromic Characterizationmentioning

confidence: 97%

Amorphous WO3 Films via “Wet” CVD of a WVI Oxoalkoxide Precursor

Basato¹,

Brescacin²,

Tondello³

2001

Chem. Vap. Deposition

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show abstract

“…The first component is close to the IR peak (at 600 cm −1 ) reported for magnetron sputtered tungsten oxide film, which is assigned to the vibration mode of the disordered W-O framework. 15,16 The second component is close to the two IR bands of crystalline WO 3 (at 800 or 807 cm −1 ). 17,18 The appearance of these two components indicates that the amorphous network in RTE1 has a short range order analogous to that in crystalline WO 3 .…”

Section: B Structurementioning

confidence: 58%

Relationship between the microstructure and nanoindentation hardness of thermally evaporated and magnetron-sputtered electrochromic tungsten oxide films

et al. 2001

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Tungsten oxide (WO x ) films were fabricated by (i) reactive thermal evaporation (RTE) at room temperature with oxygen ambient pressure P O 2 as a parameter, and (ii) reactive magnetron sputtering (RMS) with substrate temperature T s as a parameter. The film structure revealed by x-ray photoelectron spectroscopy, x-ray diffraction, density measurements, infrared absorption, and atomic force microscopy was correlated with the nanoindentation hardness H. The RTE WO x films deposited at high P O 2 were amorphous and porous, while H depended appreciably on normalized penetration depth h D (indentation depth/film thickness) due to the closing of the pores at the point of indentation. Decrease in P O 2 from 10 to 2 × 10 −3 mtorr led to smaller porosity, weaker h D dependence of H, and higher average H (measured at h D ≈ 0.2 to 0.3, for example). The RMS WO x film deposited at room temperature was amorphous and denser than all RTE films. The rise in substrate temperature T s first densified the film structure (up to 110°C) and then induced crystallization with larger grain size for T s ജ 300°C. Correspondingly, the h D dependence of H became weaker. In particular, H of the RMS sample deposited at 110°C showed a peak at h D slightly above 1 owing to pileup at the contact point of indentation. For higher T s , pileup occurred at shallower h D and the average H (measured at h D ≈ 0.2 to 0.3, for example) rose, accompanied by the increase of grain size.

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“…According to Yoshiike and Kondo [19,20], water molecules are not only physisorbed but also chemisorbed on WO 3 . The oxophilic nature of WO 3 would help in adsorbing the intermediates and thereby, maintain the surface of platinum clean.…”

Section: Resultsmentioning

confidence: 99%