Praseodymium group

A sample of the praseodymium group (praseodymium, neodymium, and element 61 most of the cerium, samarium, europium, and yttrium fission products had been removed, cerium by ceric iodate precipitations and the others by potassium carbonate digestions) was absorbed on an Amberlite IR-1 column. The elution curve is shown in Fig. 14.1. The soft P emitter (now known to be 2.62-year see Table 14.2) appeared in the position expected (by... 

Elution curve for the praseodymium group of fission products from Amberlite IR-1 (Reprinted with permission from Marinsky et al. 1947. 1947 American Chemical Society)... 

Analysis of the lanthanide-induced crystalline arrays by negative staining (Fig. 5) or freeze-fracture electron microscopy reveals obliquely oriented rows of particles, corresponding to individual Ca -ATPase molecules [119]. The unit cell dimensions for the gadolinium-induced Ca -ATPase crystals are a = 6. l A, b = 54.4 A and y = 111°. Similar cell constants were obtained for the crystals induced by lanthanum, praseodymium and calcium. The unit cell dimensions of the Ei crystals are consistent with a single Ca -ATPase monomer per unit cell. The space group of the Eptype crystals is PI [119], while that of the E2 crystals is P2 [88,90]. 

The Sr-doped praseodymium manganites and cobaltites have been studied by several groups as potential cathodes for ITSOFC. Kostogloudis et al. [116-118] systematically investigated the crystal structure, electrical conductivity, and thermal expansion properties of (Pr, Sr)Mn03, (Pr, Sr)Co03, and (Pr, Sr)(Co, Mn)03 systems. All compounds have the orthorhombic perovskite GdFe03-type structure (Pbnm... 

As indicated later (see Section VI,8), on addition of the chloride of praseodymium, europium, or other lanthanides to mono- or poly-sac-charide phosphates in D20, the signals of carbon atoms substituted with phosphate groups are recognizable, as they are displaced, relative to the rest of the 13C-n.m.r. spectrum.155 However, this diagnostic method is not applicable to sulfated polysaccharides, as signal displacements were not observed on addition of praseodymium or europium chloride to a solution of a,/3-D-galactose 6-sulfate or its sodium salt.156... 

Rare earth. One of a group of 15 chemically related elements lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. 

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. 

The LSR itself consists of a lanthanide ion, commonly europium (Eu3 + ), praseodymium (Pr3+) or ytterbium (Yb3+), and three /1-diketone anions with alkyl or perfluoroalkyl groups Rl and R2 as ligands. Perdeuterated LSRs, which do not give H signals, are commercially available. Incorporation of chiral /J-diketone ligands, mostly derived from substituted camphors, allows chiral recognition. 

Sengupta, S. K. et al., Transition Met. Chem., 2000, 25(2), 150 Three to one lanthanum and praseodymium salts were prepared. They exploded on heating above 180 C, making thermal studies difficult. Analogues without the nitro-group decompose controllably. 

Cement, laboratory, 1 189 Cerite, extraction of, 2 44 Cerium, phosphor containing strontium sulfide and, 3 23 separation of, from rare earth mixtures, 2 43, 47, 48 test for, 2 50 Cerium amalgam, 1 15 Cerium-group earths, separation of, from yttrium earths by doublesulfate method, 2 44, 46 Cerium (III) magnesium nitrate, 2Ce(N03)s-3Mg(N03)2-24H,0, separation of praseodymium from lanthanum by, 2 57 Cerium(III) nitrate, 2 51 Cerium (IV) nitrate, basic, 2 49 Cesium, cesium azide for preparation of, 1 79... 

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. 

Diphosphazane dioxide complexes of lanthanides have potential application in the solvent extraction separation of lanthanides. Reaction of lanthanide nitrate with X2P(0)NPr )-P(0)X2(L-L) yields the bis chelate complexes Ln(NC>3)(L-L)2. The structure of the praseodymium complex has been determined by X-ray diffraction and the space group is P32- There are two independent molecules in the unit cell which differ in orientation of the phenyl group. The metal ion is ten-coordinated [264]. 

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