Boiling point rare earth elements

Scandium is a soft, lightweight, silvery-white metal that does not tarnish in air, but over time, it turns yellowish-pink. It resists corrosion. Scandium reacts vigorously with acids, but not water. Scandium has some properties similar to the rare-earth elements. Although its position in group 3 places it at the head of the 17 elements of the lanthanide series of rare-earth metals, scandium, as a metal, is not usually considered a rare-earth. Scandiums melting point is l,54l°C, its boiling point is 2836°C, and its density is 2.989 glctn . 

Samarium is a yellowish metal with a melting point of 1,962°F (1,072°C) and a boiling point of about 3,450°F (1,900°C). Its density is 7.53 grams per cubic centimeter. Samarium is the hardest and most brittle of the rare earth elements. 

TABLE VII Melting Points, Boiling Points, and Crystal Structures and Volume of the Rare Earth Elements... 

Even alkoxides of rare earth elements can be synthesized by direct interaction of metals with alcohols (usually PrOH taken in 1 1 or 1 2 mixtures with toluene to increase the boiling point) [111] on reflux or addition of mercury(II) chloride as catalyst. In the latter case, the reaction is usually quite slow and thus takes long time. It is advantageous to use flne metal turnings for this purpose. 

When the boiling points of metallic impurities are much lower than the boiling point of the main metal, they can simply be distilled away in most cases. The rate and the extent of the removal by distillation of these impurity elements depend upon their partial pressures over the main metal/melt. As an example, let the feasibility of distilling magnesium and magnesium chloride from titanium and calcium from the rare earths be considered. In the firstcase, at 900 °C, the pertinent vapor pressure values are P = 4 10-11 torr, PMg = 105 torr... 

Volatilization. Many fission-product elements, including krypton, xenon, iodine, cesium (normal boiling point 705 C), strontium (1380°C), barium (1500°C), the rare earths (3200 C), and plutonium (3235°C), are more volatile than uranium (3813°C). Cubicciotti [C17], McKenzie [M5], and Motta [M8], in laboratory experiments, showed that around 99 percent of these more volatile elements could be separated from uranium by vacuum distillation at 1700 C. Because of the high temperature and severe materials problems, volatilization has not been used as a primary separation process, but does contribute to removal of the most volatile fission products in conventional reprocessing. In fractional crystalUzation or extraction with liquid metals, distillation is used to separate uranium and plutonium from more volatile solvent metals. 

BrF and CIF ) and fused meteillle fluorides. Host elements form fluorides under the conditions that UFg Is obtained. However, only a small number of these fluorides are volatile. Hyman, et al. have published a table of some 26 elements having fluorides with boiling or sublimation points of 550 C or less. Included In this group are the fluorides of boron, silicon, phosphorus, vanadium, sulfur, tungsten, bismuth, plutonium, and the fission products, germanium, arsenic, selenium, niobium, molybdenum, ruthenium, antimony, tellurium, and Iodine. The boiling point of UFg Is 5lf.6 C. Non-volatlle fluorides from which uranium Is readily separated Include those of the alkali metals, alkaline earths, rare earths, Fe, Co, Nl, Ag, Al, Bg, )ta, Tl, Fb, Zn, Cu,... 

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