Niobium-Germanium

Niobium germanide, NbgGe, is a superconductor with a high transition temperature (T, = 20K). It is prepared by CVD by the coreduction of the chlorides as follows  

The chlorides are prepared in situ and the deposition reaction temperature is 900°C.[ 11 1 

Aluminum CVD with New Gas-phase Pretreatmentusing TDMAT for ULSIMetallization, V. Vac.Sci. Tech., 13(5) 2115(Sept.-Oct. 1995) 

Pierson, H. O., Aluminum Coatings by the Decomposition of PA iy f Thin Solid Films, 45 257-264 (1977) 

Powell, C. F., Chemically Deposited Metals, mVapor Deposition, (C.F.Powell, etal., eds.), John Wiley Sons, New York (1966) 

---

Some elements found in body tissues have no apparent physiological role, but have not been shown to be toxic. Examples are mbidium, strontium, titanium, niobium, germanium, and lanthanum. Other elements are toxic when found in greater than trace amounts, and sometimes in trace amounts. These latter elements include arsenic, mercury, lead, cadmium, silver, zirconium, beryUium, and thallium. Numerous other elements are used in medicine in nonnutrient roles. These include lithium, bismuth, antimony, bromine, platinum, and gold (Eig. 1). The interactions of mineral nutrients with... 

The metal alloy, niobium germanium (Nb3Ge), is another superconductor with a much lower transition temperature (20K) with well-established characteristics and good strength. It is deposited by CVD on an experimental basis by the reaction described in Ch. 6. 

The Josephson junction is one such ultrafast superconducting switching device. Josephson junctions, which until recently operated only at liquid-helium temperature, are traditionally made of niobium-tin or niobium-germanium and are really simple connections between superconductors. They can do everything vacuum tubes and transistors do, but a lot faster. 

Maslov, V. M., Borovinskaya, I. P., and Ziatdinov, M. K., Combustion of the systems niobium-aluminium and niobium-germanium. Combust. Explos. Shock Waves, 15,41 (1979). 

The reactions of aminoalcohols, such as aminoethanol and A-methylamino-ethanol, with a number of metal alkoxides were investigated in our laboratories (6). These alcohols depict an interesting variation in the reactivity pattern and nature of the final product(s). For example, in reactions of boron, aluminum, silicon, titanium, and zirconium alkoxides with these ligands only the hydroxyl group was found to be reactive. However, with niobium, germanium, and tin... 

The tantalum carbides and silicides and tungsten carbides cited above are used for their hardness, corrosion resistance in hot environment and their semiconducting properties, while niobium alloys (niobium-germanium, niobium-aluminium...) receive much attention for their properties of superconductivity. 

Cohen U., Electrodeposition of Niobium-Germanium alloys from molten fluorides, (1983), J. Electrochem Soc., 130, 1479-85. 

Cohen U (1983) Electrodeposition of niobium-germanium alloys. J Electrochem Soc 130 1480... 

Ammonia and alcohol may be used instead of sodium alkoxides to manufacture alkoxides of titanium and other metals such as tirconium, hafnium, germanium, niobium, tantalum, aluminum, and tin. 

Aluminum, barium, beryllium, boron, dysprosium, erbium, europium, gadolinium, gallium, germanium, hafnium, holmium, lanthanum, molybdenum, neodymium, niobium, phosphorus, praseodymium, rhenium, samarium, scandium, silicon, strontium, tantalum, terbium, thulium, tin, titanium, tungsten, uranium, vanadium, ytterbium, yttrium, zirconium... 

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. 

Elements with distinctive but less sensitive Home spectra beryllium, germanium, gold, mercury, molybdenum, niobium, rhenium, selenium, silicon, titanium, tungsten. 

Aluminium, 0048 Antimony, 4901 Barium, 0200 Beryllium, 0220 Bismuth, 0226 Cadmium, 3943 Caesium, 4248 Calcium, 3916 Cerium, 3955 Chromium, 4216 Cobalt, 4193 Copper, 4261 Europium, 4286 Gallium, 4400 Germanium, 4406 Gold, 0110 Hafnium, 4594 Indium, 3579 Iridium, 4638 Lanthanum, 4672 Lead, 4876 Lithium, 4675 Magnesium, 4685 Manganese, 4695 Mercury, 4595 Molybdenum, 4707 Neodymium, 4813 Nickel, 4814 Niobium, 4811 Osmium, 4867 Palladium, 4879 Platinum, 4881 Plutonium, 4882 Potassium, 4640 Praseodymium, 4880 Rhenium, 4884 Rhodium, 4886 Rubidium, 4883 Ruthenium, 4888... 

Also, of course, there was always the icy grip of cumbersome liquid or compressed gaseous helium that the materials had to be held in if they were to superconduct. Try as they might, researchers could not get the transition temperature of all their materials up to easily manageable levels. By 1973, although several hundred materials were known to superconduct, the best that scientists were able to achieve was a Tc of 23.2° K (-418° F] with a compound of three parts niobium and one of germanium, the latter a hard metalloid with, ironically, semiconductor properties. 

---