Neodymium tungstate

Neodymium Tungstate is formed as a gelatinous precipitate on the addition of neodymium chloride to a solution of sodium tungstate. ... 

Solid-state lasers using substitutional neodymium (Nd3+ ions) as the active defects are widely available. Practical lasers contain about 1% Nd3+ dopant. The most common host materials are glass, yttrium aluminum garnet (YAG), Y3A15012, and calcium tungstate, CaW04. In the crystalline host structures, the defects responsible for amplification are NdY and Ndca-... 

Zarowin (121) measured the fluorescent lifetime of neodymium in calcium tungstate at room temperature using a multiple-sampling technique. He found different values for the 4F3/2->479/2 and the 4F3/2 4/n/2 transitions, the results being 160 16 and 230 15 /xsec, respectively. As he points out, these results are indeed very surprising. It was not clear to Zarowin whether the experimental data are suspect or whether the lifetime is indeed different. 

The quantum yields of fluorescence of the different systems have also been determined relative to a single crystal of neodymium-doped YAG for which a quantum yield of unity has been assumed (Heller, 1968a). The quantum yields obtained, even if they are accurate only within a factor of two, follow the same trend as for the lifetimes, with the highest values for the acidic solutions 0.70 and >0.75 in presence of S11CI4 and SbCls, respectively. Neutral and basic solutions are less luminescent and have quantum yields of 0.5 and 0.4, respectively. Identical measurements performed on a sodium-compensated neodymium-doped calcium tungstate crystal lead to a value of 0.5. The high quantum efficiency and the low threshold (between 2 and 40 J) of these Nd3+ SeOCl2 systems clearly demonstrate that liquids are not inherently inferior to solids as laser materials. 

In addition to the above, preparation in w/o microemulsions of nanoparticles of various other types of compounds, viz. silica-coated iron oxide, Fe203-Ag nanocomposite, oxides of ytrium, erbium, neodymium, vanadium and cobalt, titanates of barium and lead, ferrites of barium, strontium, manganese, cobalt and zinc, oxide superconductors, aluminates, zirconium silicate, barium tungstate, phosphates of calcium, aluminium and zinc, carbonates of calcium and barium, sulphides of molybdenum and sodium, selenides of cadmium and silver etc. have been reported. Preparative sources and related elaboration can be found in [24]. 

Calcium tungstate diluted with a small amount of neodymium was the first continuous wave laser (Johnson et al., 1962). Since then a number of lasers have been built using the triply ionized rare earth ions Pr, Nd, Ho, Er, and Tm (Chesler and Geusic, 1972). 

Phosphorescence and Fluorescence Many ceramics phosphoresce and fluoresce. These ceramics find applications in fluorescent lights, oscilloscope screens, television screens, electroluminescent lamps, photocopy lamps, and lasers. Lasers include tungstates, fluorides, molybdates, and garnet compositions doped with chromium, neodymium, europium, erbium, praseodymium, and so on. Ceramic phosphor is Ca5(P04)3(Cl,F) or Sr5(P04)3(Cl,F) doped with Sb and Mn. Figure 1.9 shows some configurations of fluorescent lights. 

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