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.

Tungsten chemical-mechanical polishing process using a fixed abrasive polishing pad and a tungsten layer chemical-mechanical polishing solution specifically adapted for chemical-mechanical polishing with a fixed abrasive pad

Abstract: The invention comprises tungsten chemical-mechanical polishing processes using fixed abrasive polishing pads, and to tungsten layer chemical-mechanical polishing solutions specifically adapted for chemical-mechanical polishing with fixed abrasive pads. In one implementation, a semiconductor wafer having a layer comprising tungsten at greater than or equal to 50% molar is provided. Such is positioned in proximity with a fixed abrasive chemical-mechanical polishing pad. A tungsten layer chemical-mechanical polishing solution is provided intermediate the wafer and pad. The solution comprises a tungsten oxidizing component present at from about 0.5% to 15% by volume and a pH of less than or equal to about 6.0. The tungsten comprising layer is chemical-mechanical polished with the fixed abrasive pad with the tungsten layer chemical-mechanical polishing solution being received between the wafer and the pad. In one implementation, tungsten from the layer is oxidized with a solution comprising a tungsten oxidizing component present at from about 0.5% to 15% by volume and a pH of less than or equal to about 6.0. One or both of tungsten and tungsten oxide is then polished from the tungsten comprising layer with a fixed abrasive chemical-mechanical polishing pad. In one implementation, the invention comprises a tungsten layer chemical-mechanical polishing solution.

Nickel-refractory metal substrate tapes with high cube texture stability

Abstract: The effect of different impurity levels in nickel on the quality of the primary recrystallization cube texture after intense cold rolling was investigated. Texture sharpness and thermal stability in the 99.9 at% nickel tapes could be improved by micro-alloying with molybdenum and tungsten as well as with niobium and tantalum. Furthermore, micro-alloying reduced the susceptibility of the substrate materials against grain boundary grooving at processing temperatures in the range of about 800 °C. Highly alloyed nickel with 5 at% tungsten was not susceptible to thermal etching effects independent of the processing route, i.e. melting or powder metallurgy. Cube textures were obtained for different nickel-refractory metal alloys with characteristic in-plane orientations of FWHM: 4-8°. The performance of this group of substrate materials for coating with ceramic buffer and superconductor layers could be proven by the achieved maximum critical current density of 1.2 MA cm-2 at liquid nitrogen temperature and zero magnetic field.

Crystal Structure of Monoclinic Tungsten Trioxide at Room Temperature

Abstract: The crystal structure of tungsten trioxide at room temperature has been studied by the X-ray oscillation method. The crystal has a monoclinic unit cell with a =7.30 A, b =7.53 A, c =7.68 A and β=90°54', containing eight molecules of WO 3 . c axis length is as twice as the values reported by the other authors. The space group is P 2 1 / n . The structure analysis was performed by trial and error based on inspection of the Patterson projections along a and c axes. The arrangement of tungsten atoms is similar to the structure reported by Braekken. The positions of oxygen atoms, which had been determined hitherto mainly from packing considerations, could be obtained directly from the weak reflections with odd index l . According to the obtained structure the crystal is antipolar in the directions of a , b and c axes.