Tungsten

About: Tungsten is a research topic. Over the lifetime, 35225 publications have been published within this topic receiving 456213 citations. The topic is also known as: W & element 74.

Efficient photoelectrochemical water splitting by anodically grown WO3 electrodes.

Abstract: The potentiostatic anodization of metallic tungsten has been investigated in different solvent/electrolyte compositions with the aim of improving the water oxidation ability of the tungsten oxide layer. In the NMF/H(2)O/NH(4)F solvent mixture, the anodization leads to highly efficient WO(3) photoanodes, which, combining spectral sensitivity, an electrochemically active surface, and improved charge-transfer kinetics, outperform, under simulated solar illumination, most of the reported nanocrystalline substrates produced by anodization in aqueous electrolytes and by sol-gel methods. The use of such electrodes results in high water electrolysis yields of between 70 and 90% in 1 M H(2)SO(4) under a potential bias of 1 V versus SCE and close to 100% in the presence of methanol.

Work Function of Tungsten Single Crystal Planes Measured by the Field Emission Microscope

Abstract: The work functions of the low emitting crystallographic planes of tungsten, (011) and (112), are not well known. In previous experiments scattered secondaries and some other disturbing effects covered the small emission particularly of the (011) plane. A method combining the field emission microscope with a probe collector has been applied. The current density in the (011) plane turned out to be 4 to 5 orders of magnitude smaller than in strongly emitting planes. Applying the Fowler‐Nordheim theory, φ011 was found between 5.70 and 5.99 ev and φ112 between 4.65 and 4.88 ev depending on the temperature at which the tungsten crystal has been annealed previously. This is not a temperature effect of the work function, but the result of freezing in thermal imperfections of the planes. The work function of the ideal (011) plane appears to be as high as 5.99 ev. The existence of such a high value is further suggested by the ionization of aluminum on a hot polycrystalline tungsten wire, indicating that a part of t...

Method of forming low-resistivity tungsten interconnects

Abstract: Methods and apparatus for preparing a low-resistivity tungsten film on a substrate are provided. Methods involve the formation of a tungsten nucleation layer on a substrate using pulsed nucleation layer (PNL) techniques and depositing a bulk tungsten layer thereon. Methods for forming the tungsten nucleation layer involve the use of a boron-containing species, a tungsten-containing precursor, and optionally, a silane. The methods described are particularly useful for applications where thin, low resistivity films are desired, such as interconnect applications.

Effect of vanadia and tungsten loadings on the physical and chemical characteristics of V2O5-WO3/TiO2 catalysts

Abstract: Titania-supported tungsten and vanadia oxides with different W and V loadings and calcined at different temperatures have been prepared by the sol–gel method and characterized. Large amount of tungsten (9%; w/w) provides thermal stability to WO3/TiO2 systems upon addition of vanadia. It is found that WO3 and V2O5 crystallites are formed when their concentrations are higher than those corresponding to three monolayers. DTA analyses have shown that the presence of V2O5 crystallites is not essential for the transformation of titania anatase into rutile. High reactivity in limited temperature range (225–350 °C) has been observed for the catalyst with 8% (w/w) V2O5 with a high formation of N2O amount during the SCR reaction. The catalyst with 3% (w/w) V2O5 exhibits a slight lower reactivity but with a high selectivity to N2 preserved in all working temperature.