Neodymium Element

Neodymium are known. The most stable of these are the naturally occurring Nd (half-life of 2.29 x 10 years) and °Nd (half-life of 7 x 10 years). The remaining radioactive isotopes have half-lives that are less than 11 days (Table 3.6). 

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Gr. neos, new, and didymos, twin) In 1841, Mosander, extracted from cerite a new rose-colored oxide, which he believed contained a new element. He named the element didymium, as it was an inseparable twin brother of lanthanum. In 1885 von Welsbach separated didymium into two new elemental components, neodymia and praseodymia, by repeated fractionation of ammonium didymium nitrate. While the free metal is in misch metal, long known and used as a pyrophoric alloy for light flints, the element was not isolated in relatively pure form until 1925. Neodymium is present in misch metal to the extent of about 18%. It is present in the minerals monazite and bastnasite, which are principal sources of rare-earth metals. 

The element may be obtained by separating neodymium salts from other rare earths by ion-exchange or solvent extraction techniques, and by reducing anhydrous halides such as NdFs with calcium metal. Other separation techniques are possible. 

Sihca is reduced to siUcon at 1300—1400°C by hydrogen, carbon, and a variety of metallic elements. Gaseous siUcon monoxide is also formed. At pressures of >40 MPa (400 atm), in the presence of aluminum and aluminum haUdes, siUca can be converted to silane in high yields by reaction with hydrogen (15). SiUcon itself is not hydrogenated under these conditions. The formation of siUcon by reduction of siUca with carbon is important in the technical preparation of the element and its alloys and in the preparation of siUcon carbide in the electric furnace. Reduction with lithium and sodium occurs at 200—250°C, with the formation of metal oxide and siUcate. At 800—900°C, siUca is reduced by calcium, magnesium, and aluminum. Other metals reported to reduce siUca to the element include manganese, iron, niobium, uranium, lanthanum, cerium, and neodymium (16). 

Figure 16 shows the charge-discharge cycle characteristics of alloys in which part of the nickel component was replaced with cobalt. Misch metal (Mm), which is a mixture of rare earth elements such as lanthanum, cerium, praseodymium, and neodymium, was used in place of lanthanum. It was found that the partial replacement of nickel with cobalt and the substi-... 

Calcium is generated in situ for effecting reduction in another process in which elemental sodium is introduced in the charge mixture. The production of neodymium metal or of its alloys by the reduction of neodymium sesquioxide with sodium in the presence of calcium chloride is known as the NEOCHEM process. This process was developed at the General Motors Research Laboratories in the 1980s. The overall reaction pertinent to the process can be written as... 

A common feature of catalysts based on 4 and 5f block elements is that of being able to polymerize both butadiene and isoprene to highly cistactic polymers, independently of the ligands involved. Butadiene, in particular, can reach a cistacticity as high as 99% with uranium based catalysts (3) and cistacticity of > 98% with neodymium based catalysts (4). This high tacticity does not change with the ligand nature (Fig. 1) in contrast to conventional catalysts based on 3-d block elements. A second feature of f-block catalysts is that the cis content of polymer is scarcely... 

The compounds of the rare earth elements are usually highly colored. Neodymium s compounds are mainly lavender and violet, samarium s yellow and brown, holmium s yellow and orange, and erbium s rose-pink. Europium makes pink salts which evaporate easily. Dysprosium makes greenish yellow compounds, and ytterbium, yellow-gold. Compounds of lutetium are colorless, and compounds of terbium are colorless, dark brown, or black. 

These include the following 14 elements cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmi-um, erbium, thulium, ytterbium, and lutetium. 

We were quite elated, and it appeared that it was a rich field. Now, fifty years later, I must say that it wasn t as rich as we thought. But we have over the years discovered half a dozen natural radioactive elements, and two of these, the samarium-147 with its decay to neodymium-143 and rhenium-187 with its decay to osmium-187, prove to be of use in Nuclear Dating. The importance of rhenium is that it is iron soluble while the other radioactivities are insoluble in metallic iron. In fact, the best half life we have for rhenium-187 was obtained by measuring the osmium-187 to rhenium-187 ratio in iron meteorites which had been dated by other methods. This work was started many years ago by Dr. Herr and others in Germany. The half life is 43,000,000,000 years. 

Bau M, Dulski P (1996) Distribution of yttrium and rare-earth elements in the Penge and Kuruman iron-formations, Transvaal Supergroup, South Africa. Precam Res 79 37-55 Bau M, Hohndorf A, Dulski P, Beukes NJ (1997) Sources of rare-earth elements and iron in Paleoproterozoic iron-formations from the Transvaal Supergroup, South Africa evidence from neodymium isotopes. J Geol 105 121-129... 

Neodymium - the atomic number is 60 and the chemical symbol is Nd. The name was originally neodidymium and was later shortened to neodymium, which is derived from the Greek neos for new and didymos for twin . It was discovered by the Swedish surgeon and chemist Carl Gustav Mosander in 1841, who called it didymium (or twin) because of its similarity to lanthanium which he had previously discovered two years earlier. In 1885, the Austrian chemist Carl Auer von Welsbach separated didymium into two elements. One of which he called neodymium (or new twin). 

In a sense, each element seems to have its own personality. The noble gases— helium, neon, argon, and the rest—seem aloof, independent, uninterested. Precious metals, including silver, gold, and platinum, impress me as serene, quiet, confident. Chromium, a shiny metal that forms many highly colored compounds appears to be a rock star among the elements, as does neodymium, the key element in early lasers. 

Mg, Mn and Ca in garnets with a Jarrell-Ash laser microprobe, using ruby and neodymium lasers have shown that reliable data on the abundance of the different elements can be obtained in a very short time. 

The leach liquor is first treated with a DEHPA solution to extract the heavy lanthanides, leaving the light elements in the raffinate. The loaded reagent is then stripped first with l.Smoldm nitric acid to remove the elements from neodymium to terbium, followed by 6moldm acid to separate yttrium and remaining heavy elements. Ytterbium and lutetium are only partially removed hence, a final strip with stronger acid, as mentioned earlier, or with 10% alkali is required before organic phase recycle. The main product from this flow sheet was yttrium, and the yttrium nitrate product was further extracted with a quaternary amine to produce a 99.999% product. 

In 1885 Carl Auer Baron von Welsbach (1858-1929) separated the oxides of two similar elements from didymium. He named one praseodymium from the Greek word prasios, which means green or the green twin, and he named the other element neodymium, which is derived from new and dymium and means new twin. ... 

Neodymium is the third most abundant rare-earth element in the Earths crust (24 ppm). It is reactive with moist air and tarnishes in dry air, forming a coating of Nd O, an oxide with a blue tinge that flakes away, leaving bare metal that then will continue to oxidi2e. 

As an element, neodymium is a soft silver-yellow metal. It is malleable and ductile. It can be cut with a knife, machined, and formed into rods, sheets, powder, or ingots. Neodymium can form trivalent compounds (salts) that exhibit reddish or violet-like colors. 

Although neodymium is the 28th most abundant element on Earth, it is third in abundance of all the rare-earths. It is found in monazite, bastnasite, and allanite ores, where it is removed by heating with sulfuric acid (H SO ). Its main ore is monazite sand, which is a mixture of Ce, La, Th, Nd, Y, and small amounts of other rare-earths. Some monazite sands are composed of over 50% rare-earths by weight. Like most rare-earths, neodymium can be separated from other rare-earths by the ion-exchange process. 

Using a spectrometer in 1853, Jean Charles-GaUisard de Marignac (1817—1894) suspected that dydimia was a mixture of yet-to-be-discovered elements. However, it was not until 1879 that Paul-Emile Locoq de Boisbaudran (1838—1912), using a difficult chemical fractionation process, discovered samarium in a sample of samarskite, calling it samarium after the mineral, which was named for a Russian mine official. Colonel von Samarski. Samarskite ore is found where didymia is found. Didymia ( twins ) was the original name given to a combination of the two rare-earths (praseodymium and neodymium) before they were separated and identified. 

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