Glass and rare earths

J.L. Adam, In Properties, processing and applications of glass and rare-earth doped glasses for optical fibres, D. Hewak (Ed.), EMIS Datareviews Series Vol 22, Chap. Cl.l INSPEC, London, UK, 1998. 

D. Hewak, ed., Glass and Rare-earth-doped Glasses for Optical Fibers , EMIS Datareviews Series, INSPEC, London, 1998, N° 22, p. 55. 

Duffr ne, L. and Kieffer. J. (1998). In D. Hewak (Ed.) Properties, Processing and Applications of Glass and Rare Earth-Doped Glasses for Optical Fibres, London IEE,INSPEC,p.29. 

Two classes of material will be described here - the metal dithiolenes and rare earth metallocenes. In the metal dithiolenes a strong, low energy pi-pi transistion occurs in the near IR (9.10). This can be tuned from about 700 nm to 1400 nm by altering the metal ion, substituents or charge state of the dithiolene. The dithiolenes are particularly attractive because of their optical stability which has been exploited in their use as laser Q-switch materials. In the rare earth complexes the near IR band is provided by/-/transistions of the rare earth ion rather than the cyclopentadienyl ring structure various nonlinear optical phenomena have been observed in glasses incorporating similar ions. Previous studies have shown that dicyclopentadienyl complexes such as ferrocene have off-resonant nonlinearities similar to nitrobenzene or carbon disulphide (11-13)... 

Off-line dicarbamate solvent extraction and ICP-MS analysis [317] provided part-per-trillion detection limits Cd (0.2 ppt), Co (0.3 ppt), Cu (3 ppt), Fe (21 ppt), Ni (2 ppt), Pb (0.5 ppt), and Zn (2 ppt). Off-line matrix removal and preconcentration using cellulose-immobilized ethylenediaminetetraacetic acid (EDTA) have also been reported [318]. Transition metals and rare earth elements were preconcentrated and separated from the matrix using on-line ion chromatography with a NTA chelating resin [319]. Isotope-dilution-based concentration measurement has also been used after matrix separation with a Chelex ion-exchange resin [320]. The pH, flow rate, resin volume, elution volume, and time required for isotope equilibration were optimized. A controlled-pore glass immobilized iminodiacetate based automated on-line matrix separation system has also been described [321]. Recoveries for most metals were between 62% and 113%. 

It is well-known that concentration quenching of the 5D4 luminescence is not observed in usual glasses whose rare-earth concentration is limited to a few atomic percent. In some sodium fluorophosphate glasses, whose terbium concentration is as high as 35 atm%, 5D4 luminescence quenching is found to occur at concentration of 20 atm% (3.3 1021 ions cm-3) and greater [145]. 

The manufacture of catalysts and special glasses from rare earths... 

E24.13 BeO, B2O3, and to some extent Ge02 because they involve metalloid and non-metal oxides. Transition metal and rare earth oxides are typically non-glass-forming oxides, many of which have crystalline phases. 

Table 11.6 Colours generated by transition-metal and rare earth ions in glass (After Varshneya, 1994).

The Solid State, however, kept its grains of microstructure coarsely veiled until X-ray diffraction pierced the Crystal Planes That roofed the giddy Dance, the taut Quadrille Where Silicon and Carbon Atoms will Link Valencies, four-figured, hand in hand With common Ions and Rare Earths to fill The lattices of Matter, Glass or Sand With tiny Excitations, quantitatively grand. 

The early work on phosphate glasses led to the idea that crystalline phosphates might make extremely durable waste forms, particularly for actinides. The earliest suggestion was for the use of monazite (Boatner 1978, Boatner et al. 1980, McCarthy et al. 1978, 1980). The attractive qualities of monazite as a nuclear waste form are (1) a high solubility for actinides and rare earths (10 to 20 wt %) (2) evidence from natural occurrences of good chemical durability (3) an apparent resistance to radiation damage, as natural monazites are seldom found in the metamict state, despite very high alpha-decay event doses (Boatner and Sales 1988). There have been extensive studies of monazite and apatite as potential waste form phases, and a considerable amount of work on a number of synthetic phosphate phases has been completed. 

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