Praseodymium-141, neodymium

Parameter Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium... 

Polyisoprenes of 94—98% as-1,4 content were obtained with lanthanum, cerium, praseodymium, neodymium, and other rare-earth metal ions (eg, LnCl ) with trialkyl aluminum (R3AI) (34). Also, a NdCl 2THF(C2H3)3A1 catalyst has been used to prepare 95% <7j -l,4-polyisoprene (35). <7j -l,4-Polyisoprene of 98% as-1,4 and 2% 3,4 content was obtained with organoalurninum—lanthariide catalysts, NdCl where L is an electron-donor ligand such as ethyl alcohol or butyl alcohol, or a long-chain alcohol, and is 1 to 4 (36). 

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

Important is the use of light rare earth elonents for production of hard magnetic materials. Most prominent are alloys of samarium with cobalt in the atomic ratio 1 5 or 2 17. It may also be assumed that in further development of these materials on a larger scale that praseodymium, neodymium, lanthanum and also individual heavy rare ecu h elements will be used to achieve particular effects. Interesting is the development of magnetic bubble memories based on gadolinium-galliiimrgarnets. 

The final answer came from the atomic pile. J. A. Marinsky, L. E. Glendenin, and C. D. Coryell at the Clinton Laboratories at Oak Ridge (20) obtained a mixture of fission products of uranium which contained isotopes of yttrium and the entire group of rare earths from lanthanum through europium. Using a method of ion-exchange on Amberlite resin worked out by E. R. Tompkins, J. X. Khym, and W. E. Cohn (21) they were able to obtain a mixture of praseodymium, neodymium, and element 61, and to separate the latter by fractional elution from the Amberlite column with 5 per cent ammonium citrate at pH 2.75. Neutron irradiation of neodymium also produced 61. 

Rare earth nitrates can be prepared using nitric acid to react with a corresponding oxide, hydroxide, carbonate or metal. These nitrates dissolve easily in polar solvents such as water, alcohols, esters or nitriles. They are unstable to heat as the decomposition temperature for the nitrates of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, and samarium are 510,480, 780,450, 505, 830, and 750 °C, respectively. 

These elements are usually terpositive, forming salts such as La(N03)g 6H20. Cerium forms also a w ell-defined series of salts in which it is quadripositive. This oxidation state corresponds to its atomic number, 4 greater than that of xenon. Praseodymium, neodymium, and terbium form dioxides, but not quadrivalent salts. 

Chromates of the Rare Earth Metals.—A series of isomorphous yellow chromates, sparingly soluble in water, and of general formula E2 (Cr04)3.8H30, where R=Lanthanum, Praseodymium, Neodymium, or Samarium, has been prepared. ... 

Praseodymium Neodymium... Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium... 

In another series of studies of the soluble lanthanide chlorides, rats were fed gadolinium, samarium, terbium, thulium, ytterbium, praseodymium, neodymium, lutetium, europium, dysprosium, holmium, and erbium chloride in their diet at doses of 0, 5, 50, and 500 mg kg day for 12 weeks. Only ytterbium chloride caused any significant effect, with the 500 mg kg dose causing gastric hemorrhages. The other lanthanides caused no adverse effects at the maximum 500 mg kg dose. 

FP-3 (yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, gadolinium, terbium)—are soluble ( 15 wt %) in the process alloy and are removed by selective extraction into the salt after the reduction. This is a salt-transport step and is used as the method of controlling the FP-3 concentration in the process stream and of consolidating the FP-3 for waste handling. 

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