Trivalent ytterbium

The valences of the rare-earth metals are calculated from their magnetic properties, as reported by Klemm and Bommer.14 It is from the fine work of these investigators that the lattice constants of the rare-earth metals have in the main been taken. The metals lutecium and ytterbium have only a very small paramagnetism, indicating a completed 4/ subshell and hence the valences 3 and 2, respectively (with not over 3% of trivalent ytterbium present in the metal). The observed paramagnetism of cerium at room temperature corresponds to about 20% Ce4+ and 80% Ce3+, that of praseodymium and that of neodymium to about 10% of the quadripositive ion in each case, and that of samarium to about 20% of the bipositive ion in equilibrium with the tripositive ion. 

Finally, in the last section of this chapter (Section 6.6), we will treat two aspects that are of great relevance in the optical spectroscopy of solids. First, we will introduce a semi-empirical method (due to Judd, 1962 Ofelt,1962) that analyzes the absorption spectra of trivalent rare earth ions in crystals to search for new efficient phosphors and solid state lasers. Secondly, we will treat a relatively new topic related to optical centers in solids the optically induced cooling of trivalent ytterbium doped solids. 

Giner-Chavez BI, Van Soest PJ, Robertson JB et al (1997) A method for isolating condensed tannins from crude plant extracts with trivalent ytterbium. J Sci Food Agric 74 359-368... 

At the end of the 1950 s, Crosby and Kasha reported the rather exceptional case of near-infrared luminescence of trivalent ytterbium ion in an 1 3 (Ln L) chelate occurring after intramolecular energy transfer between the organic ligand, in this case dbm (48b), and the lan-... 

Page RH, Schaffes Kl, Waide PA, Tassano JB, Payne SA, Krupke WE, Bischel WK (1998) Up-conversion-pumped luminescence efficiency of rare-earth-doped hosts sensitized with trivalent ytterbium. J Opt Soc Am B 15 996... 

The intermediate compositions in this system form two phases. The authors concluded that the tendency to form trivalent ytterbium in gadolinium is small. Although X-ray diffraction measurements were used, in this investigation, the only lattice spacing data reported were plots of a vs. at% Yb for several compositions that had been heat-treated and quenched from 500, 750 and 810°C to establish the solubility of gadolinium in ytterbium at these temperatures. 

The authors concluded that the tendency to form trivalent ytterbium in lutetium is small. The small solubility of Yb in Lu is a result of the size disparity in this system. 

The reactions with fluorinated compounds give, besides the indicated products, the five-nuclear cluster of trivalent ytterbium (Me5C5)ftYb5(p4-F)( i3-F)2(ll-F)s, which is the result of the secondary reaction of (Me5C5)2YbF with the initial R °. 

Calderazzo et al. (1966) YbCp2 THF violet-red solutions does not show any band around 1000 nm, confirming the absence of trivalent ytterbium species... 

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