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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.


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Journal ArticleDOI
TL;DR: In this paper, it was shown that the tungsten nanostructure is easily formed when the temperature is in the range 1000-2000 K, and the incident ion energy is higher than 20 eV.
Abstract: Helium irradiation on tungsten changes the surface morphology dramatically by forming a nanometre-sized fibreform structure which could bring about serious problems for fusion reactors. From the experimental results in liner divertor simulators, it is revealed that the incident ion energy and surface temperature are key parameters for the formation of the structure. It is shown that the tungsten nanostructure is easily formed when the temperature is in the range 1000–2000 K, and the incident ion energy is higher than 20 eV. Furthermore, on the basis of the helium irradiation experiments performed in the divertor simulator NAGDIS-I, the initial formation process of the nanostructure is revealed. It is shown that the nanostructure formation is related to pinholes appearing on the bulk part of the material, and then, the rough structure develops to a much finer nanostructure. The nanostructure was also observed on the molybdenum surface that was exposed to the helium plasma. It increases interest in the possibility that nanostructure formation by helium irradiation is a common phenomenon that occurs on various metals.

539 citations

Journal ArticleDOI
TL;DR: In this article, the authors used a 60 TW/5 MJ electrical accelerator located at Sandia National Laboratories to implode tungsten wire-array Z pinches, which achieved an x-ray power of ∼200 TW and an xray energy of nearly 2 MJ.
Abstract: Here Z, a 60 TW/5 MJ electrical accelerator located at Sandia National Laboratories, has been used to implode tungsten wire-array Z pinches. These arrays consisted of large numbers of tungsten wires (120–300) with wire diameters of 7.5 to 15 μm placed in a symmetric cylindrical array. The experiments used array diameters ranging from 1.75 to 4 cm and lengths from 1 to 2 cm. A 2 cm long, 4 cm diam tungsten array consisting of 240, 7.5 μm diam wires (4.1 mg mass) achieved an x-ray power of ∼200 TW and an x-ray energy of nearly 2 MJ. Spectral data suggest an optically thick, Planckian-like radiator below 1000 eV. One surprising experimental result was the observation that the total radiated x-ray energies and x-ray powers were nearly independent of pinch length. These data are compared with two-dimensional radiation magnetohydrodynamic code calculations.

525 citations

Journal ArticleDOI
TL;DR: In this article, the authors show that the performance of tungsten surfaces under intense transient thermal loads is another critical issue, since the formation of a melt layer may favor the generation of highly activated dust particles.

523 citations

Journal ArticleDOI
25 Jul 2018-Nature
TL;DR: Micrometre-sized particles of two niobium tungsten oxides have high volumetric capacities and rate performances, enabled by very high lithium-ion diffusion coefficients.
Abstract: The maximum power output and minimum charging time of a lithium-ion battery depend on both ionic and electronic transport. Ionic diffusion within the electrochemically active particles generally represents a fundamental limitation to the rate at which a battery can be charged and discharged. To compensate for the relatively slow solid-state ionic diffusion and to enable high power and rapid charging, the active particles are frequently reduced to nanometre dimensions, to the detriment of volumetric packing density, cost, stability and sustainability. As an alternative to nanoscaling, here we show that two complex niobium tungsten oxides-Nb16W5O55 and Nb18W16O93, which adopt crystallographic shear and bronze-like structures, respectively-can intercalate large quantities of lithium at high rates, even when the sizes of the niobium tungsten oxide particles are of the order of micrometres. Measurements of lithium-ion diffusion coefficients in both structures reveal room-temperature values that are several orders of magnitude higher than those in typical electrode materials such as Li4Ti5O12 and LiMn2O4. Multielectron redox, buffered volume expansion, topologically frustrated niobium/tungsten polyhedral arrangements and rapid solid-state lithium transport lead to extremely high volumetric capacities and rate performance. Unconventional materials and mechanisms that enable lithiation of micrometre-sized particles in minutes have implications for high-power applications, fast-charging devices, all-solid-state energy storage systems, electrode design and material discovery.

515 citations

Journal ArticleDOI
TL;DR: In this article, temperature-programmed reaction between MoO3 or WO3 with NH3 provides a new way to prepare Mo2N and W2N powders with specific surface areas as high as 220 and 91 m2 g−1, respectively, corresponding to 3- to 4-nm crystallites.

506 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,055
20222,162
2021902
20201,216
20191,447
20181,372