Samarium lanthanide metals lutetium

The primary reason for distillation/sublimation as a purification process is to separate the non-volatile tantalum from the higher melting lanthanide metals gadolinium through erbium, plus lutetium, and scandium and yttrium. As explained earlier samarium, europium and ytterbium are prepared in a vacuum process that involves their distillation from the reaction mixture they may be re-sublimed to achieve a higher purity. 

Lanthanum (La) and lanthanide metals neodymium (Nd), samarium (Sm) and lutetium (Lu) as well as yttrium (Y) with pentamethylcyclopentadienyl (// -MesCs = Cp ) and a silicon-bridged bis(tetramethylcyclopentadienyl) (Me4C5-SiMe2-C5Me4 = Me2SiCp"2) ligand have been proved to be excellent and unique hydrosilylation catalysts which exhibit distinctive features in comparison with traditional Group VEEI late-transition metal catalysts" "". ... 

Recently, rare-earth metal complexes have attracted considerable attention as initiators for the preparation of PLA via ROP of lactides, and promising results were reported in most cases [94—100]. Group 3 members (e.g. scandium, yttrium) and lanthanides such as lutetium, ytterbium, and samarium have been frequently used to develop catalysts for the ROP of lactide. The principal objectives of applying rare-earth complexes as initiators for the preparation of PLAs were to investigate (1) how the spectator ligands would affect the polymerization dynamics (i.e., reaction kinetics, polymer composition, etc.), and (2) the relative catalytic efficiency of lanthanide(II) and (III) towards ROPs. 

Here, the so-called heavy lanthanides include the elements from samarium to-lutetium, except for ytterbium and europium which behave like bivalent metals and have unique properties. For these heavy-lanthanide-carbon systems, no complete phase diagram was found, only some information about the formation and the crystal structure of the carbides is available. On the basis of these data the general characteristics of the phase diagrams of the heavy-rare-earth-carbon systems can be summarized. In this case the yttrium-carbon phase diagram may be regarded as the best prototype available for compounds of the heavy lanthanide systems with carbon. 

Lundin (1966) tried to include alloys of the lanthanum-lutetium system in his study of the formation of the samarium-type structure in intra rare earth alloys. The wide differences in the melting points (La 918°C Lu 1663°C) and densities (La 6.146 g/cm Lu 9.841 g/cm ) allowed the lutetium to settle to the bottom of molten lanthanum during the alloying process. Alloys were inverted and remelted several times to improve the homogeneity. Lundin reported (1) lanthanum-lutetium alloys formed a complex microstructure that had a different appearance than that of the samarium-type structure formed in the other alloy systems between a light and a heavy lanthanide or yttrium metal and (2) X-ray analysis failed to confirm the... 

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