Didymium oxide

Yttria and the rare earths find a variety of specialized applications. Y2O3 is used to produce yttria stabilized zirconia ceramics. Cerium, neodynium, and didymium oxides (a... 

They are again dissolved in water, and precipitated with potassium hydrate. The precipitate is didymium oxide hydrate. When filtered on paper it is bluish violet. During filtration and wash it rapidly takes up carbonic acid and thereby changes its colour to a slightly reddish violet. After ignition didymium oxide is obtained... (Berzelius 1844a,b). 

Figure 2.24 Didymium oxide UV/VIS wavelength reference spectra, from a sealed quartz cell containing didymium oxide in perchloric acid solution. (Courtesy of Starna Cells, Inc., Atascadero, CA, www.starnacells.com.)...

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. 

Lanthanum - the atomic number is 57 and the chemical symbol is La. The name derives from the Greek lanthanein for to be hidden or to escape notice because it hid in cerium ore and was difficult to separate from that rare earth mineral. It was discovered by the Swedish surgeon and chemist Carl-Gustav Mosander in 1839. In 1842, Mosander separated his lanthanium sample into two oxides for one of these he retained the name lanthanum and for the other he gave the name didymium (or twin). 

A commercial mixture of several of the rare-earth elements is called didymium (Di). It is neither an element nor a compound, but is used to name the mixture of oxides and salts of most of the rare-earth elements that are extracted from the ore monazite. Another unique substance, called misch metal, is an alloy of iron and several rare-earth elements (La, Ce, and Pr). This mixture is pyrophoric, which means it sparks when scratched. This is why it is used for cigarette-lighter flints. 

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. ... 

The element was discovered hy von Welshach in 1885 after he succeeded in fractionating ammonium didymium nitrate, thus splitting didymia into two new rare earths. Earlier, in 1841, Mosander extracted a rose-colored oxide from cerite, which he named didymium and which actually was a mixture of two rare earth elements. These two new elements were named hy von Welshach as praseodymia (green twin) and neodymia (new twin). 

In 1841 Mosander had treated lanthana with dilute nitric acid, and had extracted from it a new rose-colored oxide, which he believed contained a new element. He named the new metal didymium because, as he said, it seemed to be an inseparable twin brother of lanthanum (27, 29, 46). 

Arsenites of the Rare Earth Metals.—When cerium dioxide is heated with arsenious oxide some oxidation of the latter occurs, but the product appears to be a mixture of oxides.5 Didymium hydrogen orthoarsenite, Di2(HAs03)3, has been obtained6 as a white, granular, insoluble powder by boiling didymium hydroxide with an aqueous solution of arsenious oxide. Lanthanum hydrogen orthoarsenite, La2(HAs03)3, has been prepared in a similar manner. The existence of these compounds needs confirmation, however.7... 

Many metal chlorides when heated with an excess of nitric acid are converted into the nitrates. Thus, J. L. Smith found that the transformation occurs with potassium or sodium chloride in the presence of 7 to 8 parts of nitric acid J. S. Stas said that at 40°-50°, potassium, sodium, or lithium chloride require respectively 3, 4, and 5-5 parts of nitric acid. J. L. Smith said that ammonium chloride and nitric acid yield nitrous oxide. H. Wurtz found that auric, cadmium, cerium, lanthanum, didymium, ferric, and platinic chlorides are decomposed by nitric acid incompletely and with difficulty. S. Schlesinger said that the two copper chlorides, mercurous, zinc, and lead chlorides, are decomposed, but, added H. Wurtz, with difficulty and incompletely while mercuric ajid silver chlorides are not attacked. F. Rose found cobalt amminochlorides are readily converted into the nitrate. 

During the course of the 19th century the number of known elements increased greatly. It happened that substances which were first considered to be elements were later found to be further divisible. Thus Lavoisier still considered calcium oxide, CaO, as an element and in the Rare Earth Group the element55 didymium was only separated into neodymium and praseodymium as late as 1885. 

Therefore, Brauner was highly inferesfed in the higher oxides of didymium. Mosander, de Marignac, Hermann, and Zschiesche had all observed that didymium forms besides fhe grey oxide Di20a a higher... 

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