Rare earth metal-containing

Fluorescence spectroscopy has also been widely used for investigating microviscosity in carbohydrates,deformation of poly(vinyl alcohol),composition of rare-earth metal-containing polymers,crystallinity in polyolefins and... 

M,M. ..)P04, is the second most important rare earth metal-containing ore and is also rich in cerium. Cerium is actually more abundant than copper in the Earth s crust. 

RARE EARTH METAL CONTAINING POLYMERS ENERGY TRANSFER FROM URANYL TO EUROPIUM IONS IN lONOMERS... 

With the smaller, harder rare earth elements (Gd through Lu), such compounds have never been seen, except for scandium where scandium-defrcient hexagonal perovskites, ASc Xs (A = Rb, Cs X = Cl, Br, I), have been observed. These are discussed together with the perovskite-type halides of R = Sm, Eu, Dy, Tm, Yb below. All other complex hahdes with reduced rare earth metals contain clusters and are discussed in Rare Earth Metal Cluster Complexes. 

Bastnasite is a mixed metal carbonate fluoride, (M,M. ..)C03p. The composition varies with the source of the mineral, but the dominant component is cerium ( 50%), followed by lanthanum (20-30%), neodymium (12-20%) and praseodymium (pa5%). Each of the other rare earth metals (except for promethium which does not occur naturally) typically occurs to an extait of <1%. Monazite, (M,M. ..)P04, is the second most important rare earth metal-containing ore and is also rich in cerium. Cerium is actually more abundant than copper in the Earth s cmst. 

Okamoto, Y., Ueba, Y., Dzhnibekov, N. F., Banks, E. Rare earth metal containing polymers. 3. Characterization of ion-containing polymer structures using rare earth metal fluorescence probes. Macromolecules, 14,17-22 (1981). 

As with other rare-earth metals, except for lanthanum, europium ignites in air at about 150 to I8O0C. Europium is about as hard as lead and is quite ductile. It is the most reactive of the rare-earth metals, quickly oxidizing in air. It resembles calcium in its reaction with water. Bastnasite and monazite are the principal ores containing europium. 

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. 

AHoy M16630 (ZE63A) which contains rare-earth metals and zinc, is designed to take advantage of a newer he at-treatment technique involving inward diffusion of hydrogen and formation of zirconium hydride [7704-99-6]. The alloy is heated in hydrogen at 480°C for 10, 24, or 72 hours for 6.3,... 

A residual phase, usually consisting of insoluble fluorides and oxyfluorides of alkali earth and rare earth metals, is separated from the solution by filtration. The mechanism of the chemical decomposition of raw materials of the tantalum- and niobium-containing oxide type seems to be complicated, and unfortunately, the process has yet to be adequately investigated. 

The crystal structures of the borides of the rare earth metals (M g) are describedand phase equilibria in ternary and higher order systems containing rare earths and B, including information on structures, magnetic and electrical properties as well as low-T phase equilibria, are available. Phase equilibria and crystal structure in binary and ternary systems containing an actinide metal and B are... 

Almost all of the rare-earth metal/rare-earth metal tri-iodide systems, R/RI3, contain binary phases with the rare-earth element in an oxidation state lower than -1-3 ( reduced rare-earth metal iodides) [3, 7, 10-13]. More common is the oxidation state -i-2. Elements that form di-iodides RI2 are illustrated in Fig. 4.1. 

But first the synthesis had to come John was interested in reduced metal halides, particularly for the post-transition metals cadmium, galHum, and bismuth (his Ph.D. dissertation was on anhydrous aluminum halides and mixed halide intermediates, a good start for what was to come ). However, he was not yet actively interested in rare-earth metals and their remarkable solubility in their halides. But these elements lured him one floor below where Adrian Daane headed the metallurgy section of Spedding s empire. He knew how to produce rare-earth metals with high purity and in sufficient quantity and also how to handle tantalum containers. What if one gave it a tr/ and reduced some rare-earth metal halides (John insists that this term is used correctly) from their respective metals at high temperatures under appropriate conditions. 

Exploratory solid state synthesis seems to be the only workable route to new phases because of a general inability to predict relative phase stabilities and thence structures or compositions , published in K4La6li40s A new Structure Type for Rare-Earth-Metal Cluster Compounds that Contain Discrete Tetrahedral K4l Units. S. Uma, J.D. Corbett, Inorg. Chem. 1999, 38, 3831-3835. 

One of the most exciting developments in materials science in recent years involves mixed oxides containing rare earth metals. Some of these compounds are superconductors, as described in our Chemistry and Technology Box. Below a certain temperature, a superconductor can carry an immense electrical current without losses from resistance. Before 1986, it was thought that this property was limited to a few metals at temperatures below 25 K. Then it was found that a mixed oxide of lanthanum, barium, and copper showed superconductivity at around 30 K, and since then the temperature threshold for superconductivity has been advanced to 135 K. 

Nearly all transition metals are oxidized readily, so most ores are compounds in which the metals have positive oxidation numbers. Examples include oxides (Ti02, mtile Fc2 O3, hematite C112 O, cuprite), sulfides (ZnS, sphalerite M0S2, molybdenite), phosphates (CeP04, monazite YPO4, xenotime both found mixed with other rare earth metal phosphates), and carbonates (FeC03, siderite). Other minerals contain oxoanions (MnW04, wolframite) and even more complex stmctures such as camotite, K2 (002)2 ( 4)2 2 O ... 

Pellegrini, J.P. Jr. and Strange, H.O. "Mineral Oil Containing A Rare Earth Metal Diester... 

---