US pioneers ‘high speed’ tiny tungsten

Pulsed laser synthesis of carbon-overdoped tungsten with a body-centered orthorhombic structure and planar defects

“…13) 1 and stability as an α-type bcc structure (space group Im3m) with a positive Clausius-Clapeyron (ΔT/ΔP) slope in a wide P-T range. 2 Having high mechanical strength and hardness (21)(22)(23)(24)(25), 3 good creep resistance, metal barrier performance and patternability, 4 excellent electrical conductivity 5 and fair chemical stability, 6 nanostructured W was shown to be useful as a cold-cathode material and for application in high-temperature devices. 7,8 Nanostructured W also performed excellently as an absorbing layer in X-ray masks and mirrors, 9 photonic crystals, 10 interconnectors on Sibased devices, 11,12 and metallization layers 13 by the selective crystalline polymorphs in the films.…”

“…23 Recently, α-W nanowires elongated along the [100] direction, with a tetragonal-like shape yet still with a bcc structure, have been synthesized by chemical vapor deposition (CVD) under the catalytic effect of Ni particles. 24 A number of physical and chemical methods have been used to manufacture nanostructured W. Notable among them are the controlled plasma synthesis, [25][26][27][28] microwave plasma route, 29 RF induction thermal plasma synthesis, 30 magnetron sputtering, 31 high energy ball milling, 32 equal channel angular processing, 33 combustion method, 34 electrical wire explosion, 35 thermal decomposition of tungsten hexacarbonyl, 36 electron-beam-induced selective deposition 37 and chemical vapor synthesis in a thermal reactor. 38 Little attention was paid to the special grain boundaries of W nanoparticles with a bcc structure in contrast to the well-documented oriented attachment growth of nanocrystals with other crystal structures as summarized in ref.…”

Nature and distribution of tungsten oxides in porous Vycor glass

“…Tungsten oxides are defect structures that exhibit different tungsten/oxygen ratios, different crystallographic forms and different levels of crystallinity often in the same particle or aggregate [26][27][28][29][30][31][32][33]. To a significant extent, the specific oxide obtained depends on the method and details of the synthesis.…”

“…In the absence of air, or under H 2 or NH 3 atmospheres, however, calcination leads to the formation mixed valence oxides that are collectively referred to as tungsten blue oxides (TBOs). TBO is a complex aggregate composed of crystalline and amorphous phases that contain, in addition to WO 3 , differing amounts of tungsten bronzes, the β-oxide (WO 2.9 or W 20 O 58 ), the γ-oxide (WO 2.72 or W 18 O 49 ), and WO 2 [26][27][28][29][30][31][32][33].…”

“…One is a small, ≤1 nm diameter, amorphous, hydrated oxide aggregate containing W 6+ that converts to monoclinic WO 3 on heating. The other is a mixed valence aggregate containing tungsten in different oxidation states that spectroscopically resembles commercially produced TBO [26][27][28][29][30][31][32][33]. The relative amounts of the two classes of oxides formed depend on whether PVG is polished or not with the largest amount of the mixed valence oxide formed in the unpolished glass.…”