Niobium superconducts

G. Westmacott, F. Zhong, M. Frank, S. Friedrich, S. E. Labov, and W. H. Benner. Investigating Ion-Surface Collisions with a Niobium Superconducting Tunnel Junction Detector in a Time-of-Flight Mass Spectrometer. Rapid Commun. Mass Spectrom., 14(2000) 600-607. 

It is used in arc-welding rods for stabilized grades of stainless steel. Thousands of pounds of niobium have been used in advanced air frame systems such as were used in the Gemini space program. The element has superconductive properties superconductive magnets have been... 

Special Alloys. AHoys of tin with the rater metals, such as niobium, titanium, and 2kconium, have been developed. The single-phase alloy Nb Sn [12035-04-0] has the highest transition temperature of any known superconductor (18 K) and appears to keep its superconductivity in magnetic... 

Titanium alloyed with niobium exhibits superconductivity, and a lack of electrical resistance below 10 K. Composition ranges from 25 to 50 wt % Ti. These alloys are P-phase alloys having superconducting transitional temperatures at ca 10 K. Thek use is of interest for power generation, propulsion devices, fusion research, and electronic devices (52). 

Superconductivity. One potential future use of vanadium is in the field of superconductivity. The compound V Ga exhibits a critical current at 20 T (20 X lO" G), which is one of the highest of any known material. Although niobium—zirconium and Nb Sn have received more attention, especiahy in the United States, the vanadium compound is being studied for possible future appHcation in this field since V Ga exhibits a critical temperature of 15.4 K as opposed to 18.3 K for Nb Sn. 

Oxide superconductors have been known since the 1960s. Compounds such as niobium oxide [12034-57-0] NbO, TiO, SrTi02, and AWO, where A is an alkah or alkaline earth cation, were found to be superconducting at 6 K or below. The highest T observed in oxides before 1986 was 13 Kin the perovskite compound BaPb Bi O, x = 0.27. Then in 1986 possible superconductivity at 35 K in the La—Ba—Cu—O compound was discovered (21). The compound composition was later determined to be La 85 A the Y—Ba—Cu—O system was pubUshed in 1987 and reported a transition... 

Niobium finds use in the production of numerous stainless steels for use at high temperatures, and Nb/Zr wires are used in superconducting magnets. The extreme corrosion-resistance of tantalum at normal temperatures (due to the presence of an exceptionally tenacious film of oxide) leads to its application in the construction of chemical plant, especially where it can be used as a liner inside cheaper metals. Its complete inertness to body fluids makes it the ideal material for surgical use in bone repair and internal suturing. 

The niobium-zirconium wire used remains superconducting at 4° K. even in the strong field of the solenoid itself. The unique feature of the new apparatus is the very high field homogeneity in the sample region (2 cm. diameter sphere) kept at room temperature (34). 

Pike, G., Pierson, H. O., Mullendore, A., and Schirber, J., Superconducting Thin Film Niobium Carbonitrides on Carbon Fibers, / / . Polymer Symp., No. 29, pp. 71-81, John Wiley Sons, New York (1976)... 

Brennfleck, K., Dietrich, M., Fitzer, E., andKehr, D., Chemical Vapor Deposition of Superconducting Niobium Carbonitride Films on Carbon Fibers, Eroc. 7th Int. Conf. on CVD, (T. Sedgwick andH. Lydtin, eds.), pp. 300-314, Electrochem Soc., Pennington, NJ 08534 (1979)... 

Early work on superconductors concentrated on metals or metal mixtures (alloys). Niobium alloys are particularly good superconductors, and in 1973 a niobium alloy, Nb3Ge, was found to have Tc — 23 K, the highest known value for a metal superconductor. In 1986, a ceramic oxide with formula La2- Ba CuOq was found to show superconductivity at 30 K. Through intense research efforts on ceramic oxides, YBa2 C U3 Oj-, with Tc — 93 K, was discovered in 1987. 

Many of uses of tin are also those of lead, because the metals form useful alloys. When lead is alloyed with a few percent of tin, it becomes harder and more durable. Although other compositions are produced, common solder consists of about an equal mixture of tin and lead. An alloy known as type metal contains about 82% Pb, 15% Sb, and 3% Sn, and pewter contains approximately 90% tin that is alloyed with copper and antimony. Babbitt, an alloy used in making bearings, contains 90% Sn, 7% Sb, and 3% Cu. Tin is also used to coat other metal objects to retard corrosion, and a tin-niobium alloy is used in superconducting magnets. 

When zirconium is alloyed with niobium, it becomes superconductive to electricity at temperatures near absolute zero Kelvin (—273°C). 

Niobium is a soft grayish-silvery metal that resembles fresh-cut steel. It is usually found in minerals with other related metals. It neither tarnishes nor oxidizes in air at room temperature because of a thin coating of niobium oxide. It does readily oxidize at high temperatures (above 200°C), particularly with oxygen and halogens (group 17). When alloyed with tin and aluminum, niobium has the property of superconductivity at 9.25 Kelvin degrees. 

Niobium alloyed with germanium becomes a superconductor of electricity that does not lose its superconductivity at 23.2° Kelvin as large amounts of electrical current are passed through it, as do some other superconductive alloys. In the pure metallic state, niobium wires are also superconductors when the temperatures are reduced to near absolute zero (—273°C). Niobium alloys are also used to make superconductive magnets as well as jewelry. 

Niobium is a very important metal in both ferrous and nonferrous metallurgy. As an additive to alloys or when alloyed with other metals niobium imparts high mechanical strength, high electrical conductivity, and ductihty to alloys. It enhances corrosion resistance of most alloys. The metal and several of its alloys exhibit superconductivity. Nobium is used as an additive in... 

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