Oxidation of tungsten and tungsten carbide in dry and humid atmospheres

Warren, A.; Nylund, Anders; Olefjord, I.

doi:10.1016/s0263-4368(96)00027-3

Cited by 191 publications

(94 citation statements)

References 20 publications

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“…A 4f 7/2 peak around 32.0 eV is attributed to W 2+ [71][72], while metallic tungsten signals emerge at 31.2-31.4 eV [70][71]. On the other hand, in the case of W 4+ in a conducting oxide environment a compound peak shape consisting of spin-orbit doublets of a main peak and a satellite was suggested [74][75], as a result of co-existence of two fundamentally differently screened final states. The 4f 7/2 peak of W 4+ appears around 32.8-34.0 eV [70][71]74].…”

Section: Xps Analysis Of the Mixed Oxide Materialsmentioning

confidence: 97%

“…On the other hand, in the case of W 4+ in a conducting oxide environment a compound peak shape consisting of spin-orbit doublets of a main peak and a satellite was suggested [74][75], as a result of co-existence of two fundamentally differently screened final states. The 4f 7/2 peak of W 4+ appears around 32.8-34.0 eV [70][71]74]. The air-exposed surface of WO 2 is reported to be covered by a WO 3 layer [70,73].…”

Section: Xps Analysis Of the Mixed Oxide Materialsmentioning

confidence: 99%

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Preparation and characterization of novel Ti0.7W0.3O2–C composite materials for Pt-based anode electrocatalysts with enhanced CO tolerance

Gubán

Borbáth

Pászti

et al. 2015

Applied Catalysis B: Environmental

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Ti-based electroconductive mixed oxides were deposited onto activated carbon by using three different sol-gel-based multistep synthesis routes. As demonstrated by X-ray diffraction, high crystallinity of the tungsten-loaded rutile was achieved by a sequence of annealing in inert atmosphere at 750°C and a short reductive treatment at 650°C.Formation of the rutile phase on the carbon support before the high temperature treatment has been proved to be the prerequisite for complete W incorporation into the rutile lattice. The structural and compositional properties of the mixed oxides were explored by transmission electron microscopy, temperature programmed reduction and X-ray photoelectron spectroscopy. Anode electrocatalysts were formulated by loading the composite of the activated carbon and the Ti-based electroconductive mixed oxides with 40 wt% Pt. Enhanced CO tolerance along with considerable stability was demonstrated for the electrocatalyst prepared using the Ti 0.7 W 0.3 O 2 -C composite material with high degree of W incorporation.

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Section: Xps Analysis Of the Mixed Oxide Materialsmentioning

confidence: 97%

Section: Xps Analysis Of the Mixed Oxide Materialsmentioning

confidence: 99%

Preparation and characterization of novel Ti0.7W0.3O2–C composite materials for Pt-based anode electrocatalysts with enhanced CO tolerance

Gubán

Borbáth

Pászti

et al. 2015

Applied Catalysis B: Environmental

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“…Among two stable tungsten oxides of WO 2 and WO 3 , WO 3 is the most thermodynamically stable oxide at low temperature and atmospheric pressure. Thermal oxidation of W films is strongly dependent on the temperature with a marked increase in oxidation rate at temperatures above 300 C. 28,29 However, high temperature oxidation (>600 C) often produces cracks due to the high stress between WO 3 and W. 30 After thermal oxidation at 350 C for 2 h, the top alumina layer remains unchanged but $10 nm of tungsten oxide can be clearly seen on the surface of the nanocavities. The tungsten oxide shrinks the size of nanocavities but does not clog the nanochannel, presumably due to slow oxidation rate as the result of small volume for oxygen diffusion.…”

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confidence: 99%

Field effect modulated nanofluidic diode membrane based on Al2O3/W heterogeneous nanopore arrays

Wildhaber

Bertsch

et al. 2013

Applied Physics Letters

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We developed Al2O3/W heterogeneous nanopore arrays for field effect modulated nanofluidic diodes. They are fabricated by transferring self-organized nanopores of anodic aluminium oxide into a W thin film. The nanopores are ∼20 nm in diameter and 400 nm in length. After mild oxidation, approximately 10 nm WO3 grows on the surface of W, forming a conformal and dense dielectric layer. It allows the application of an electrical field through the surrounding W electrode to modulate the ionic transport across the entire membrane. Our experimental findings have potential applications in high throughput controlled delivery and electrostatic sorting of biomolecules.

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“…In General, tungsten metal is oxidized to WO 3 in an oxygen atmosphere. 8 In this oxidation process, the surface of the tungsten wire turns to a porous structure due to the density difference of W metal (19.35 g/cm 3 ) and WO 3 (7.16 g/cm 3 ). 9 Therefore, it can be concluded that a good stability of the W-tip-Quartz-REF is mainly due to the porous structure of WO 3 formed on the surface of the tungsten wire, which provides additional ion conducting path.…”

Section: Resultsmentioning

confidence: 99%

Self-optimizing control

Horowitz

Proceedings of the 36th IEEE Conference on Decision and Control

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Oxidation of tungsten and tungsten carbide in dry and humid atmospheres

Cited by 191 publications

References 20 publications

Preparation and characterization of novel Ti0.7W0.3O2–C composite materials for Pt-based anode electrocatalysts with enhanced CO tolerance

Preparation and characterization of novel Ti0.7W0.3O2–C composite materials for Pt-based anode electrocatalysts with enhanced CO tolerance

Field effect modulated nanofluidic diode membrane based on Al2O3/W heterogeneous nanopore arrays

Self-optimizing control

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