Niobium

Abstract: New two-dimensional niobium and vanadium carbides have been synthesized by selective etching, at room temperature, of Al from Nb2AlC and V2AlC, respectively. These new matrials are promising electrode materials for Li-ion batteries, demonstrating good capability to handle high charge–discharge rates. Reversible capacities of 170 and 260 mA·h·g–1 at 1 C, and 110 and 125 mA·h·g–1 at 10 C were obtained for Nb2C and V2C-based electrodes, respectively.

Abstract: A-review is given on developments and improvements in process technology for fabricating beryllium, chromium, hafnium, molybdenum, niobium, rhenium, tantalum, tungsten, and zirconium. The references given cover the period June 1960 through May 1961. (N.W.R.)

Abstract: Lithium metal oxides with the nominal composition Li5La3M2O12 (M = Nb, Ta), possessing a garnetlike structure, have been investigated with regard to their electrical properties. These compounds form a new class of solid-state lithium ion conductors with a different crystal structure compared with all those known so far. The materials are prepared by solid-state reaction and characterized by powder XRD and ac impedance to determine their lithium ionic conductivity. Both the niobium and tantalum members exhibit the same order of magnitude of bulk conductivity (∼10−6 S/cm at 25°C). The activation energies for ionic conductivity (<300°C) are 0.43 and 0.56 eV for Li5La3Nb2O12 and Li5La3Ta2O12, respectively, which are comparable to those of other solid lithium conductors, such as Lisicon, Li14ZnGe4O16. Among the investigated materials, the tantalum compound Li5La3Ta2O12 is stable against reaction with molten lithium. Further tailoring of the compositions by appropriate chemical substitutions and improved synthesizing methods, especially with regard to minimizing grain-boundary resistance, are important issues in view of the potential use of the new class of compounds as electrolytes in practical lithium ion batteries.

Abstract: A method of forming a metal layer having excellent thermal and oxidation resistant characteristics using atomic layer deposition is provided. The metal layer includes a reactive metal (A), an element (B) for the amorphous combination between the reactive metal (A) and nitrogen (N), and nitrogen (N). The reactive metal (A) may be titanium (Ti), tantalum (Ta), tungsten (W), zirconium (Zr), hafnium (Hf), molybdenum (Mo) or niobium (Nb). The amorphous combination element (B) may be aluminum (Al), silicon (Si) or boron (B). The metal layer is formed by alternately injecting pulsed source gases for the elements (A, B and N) into a chamber according to atomic layer deposition to thereby alternately stack atomic layers. Accordingly, the composition ratio of a nitrogen compound (A—B—N) of the metal layer can be desirably adjusted just by appropriately determining the number of injection pulses of each source gas. According to the composition ratio, a desirable electrical conductivity and resistance of the metal layer can be accurately obtained. The atomic layers are individually deposited, thereby realizing excellent step coverage even in a complex and compact region. A metal layer formed by atomic layer deposition can be employed as a barrier metal layer, a lower electrode or an upper electrode in a semiconductor device.

Abstract: Jet turbine engines have benefited from decades of development of nickel-based superalloys, which have allowed a steady increase in engine operating temperatures and led to improved performance and efficiency. However, operating temperatures are now reaching limits posed by the melting temperatures ( T m) of these materials. New materials, including alloys based on metals with higher melting points, such as molybdenum (Mo) and niobium (Nb) alloyed with silicon (Si), are now being seriously examined as alternatives by academic and industrial groups.