Europium doping

Europium oxide is now widely used as a phospor activator and europium-activated yttrium vanadate is in commercial use as the red phosphor in color TV tubes. Europium-doped plastic has been used as a laser material. With the development of ion-exchange techniques and special processes, the cost of the metal has been greatly reduced in recent years. 

A. R. Bugos, S. W. Allison, and M. R. Cates, Laser-induced fluorescent properties of europium-doped scandium orthophosphate phosphors for high-temperature sensing applications, Proc. of IEEE 1991 Southeast Conf, 1143-1147 (1991). 

Similar to chemical vapor deposition, reactants or precursors for chemical vapor synthesis are volatile metal-organics, carbonyls, hydrides, chlorides, etc. delivered to the hot-wall reactor as a vapor. A typical laboratory reactor consists of a precursor delivery system, a reaction zone, a particle collector, and a pumping system. Modification of the precursor delivery system and the reaction zone allows synthesis of pure oxide, doped oxide, or multi-component nanoparticles. For example, copper nanoparticles can be prepared from copper acetylacetone complexes [70], while europium doped yttiria can be obtained from their organometallic precursors [71]. 

Matos JR, Mercuri LP, Jaroniec M, Kruk M, Sakamoto Y, Terasaki O (2001) Synthesis and characterization of europium-doped ordered mesoporous silicas. J Mater Chem 11 2580-2586... 

Crystal. Trivalent europium-doped compounds fluoresce a distinctive red color under ultraviolet excitation. This red emission, corresponding to the SD0->1F1 transition, often appears to the eye to be much weaker than the characteristic green emissions from terbium in the same hosts. This may be quite deceptive, since the human eye has very poor sensitivity to red in comparison to green. 

For the 1 per cent europium-doped sample, a buildup and decay type of curve similar to that of Chang was found. This, of course, indicates a slow internal conversion to the 5D0 metastable level. From this rise and decay... 

Measurements were made with a cathode-ray beam switched on and off with a flat-topped pulse having 20 nsec rise and fall times. For the europium-doped sample, the rise time to 90 per cent of full intensity was 10 4 sec the decay to 10 per cent luminescence was also 10 4 sec. 

Europium doped barium aluminates of the type Bai xEuxMg2Ali6027 are used as a blue component in fluorescent lamps, and are also being investigated for possible use in flat panel displays. The crystal structure of this material is characterized by an intergrowth of spinel and magnetoplumbite units (See 3.4.2 and 3.11). 

In practice, a single crystal of europium-doped lanthanum fluoride (K,p = 2 X 10" ) responds in a matter of seconds according to (13-4) to fluoride ion activity in solutions containing fluoride from about 1 Af to 10" M. Europium doping increases fluoride mobility by introducing lattice disorder. Hydroxide ion, beginning at about 10" Af, is the principal interference, probably the result of competition due to the low solubility of lanthanum hydroxide. 

Cates, M.R. Allison, S.W. Franks, L.A. Borella, H.M. Marshall, B.R. Noel, B.W. Laser-induced fluorescence of europium-doped yttrium oxide for remote high-temperature thermometry. Proc. Laser Inst. Am. 1985, 142, 49-51. 

Figure 5 Emission spectrum of europium-doped silica gel-glass.

SoUdState CrystaMne and Pressed-PeOet Electrodes. There are two basic types of crystalline-based electrodes. The first is exemplified by the fluoride electrode, with a europium-doped LaFs single crystal as the sensor. The LaFg crystal is sealed into the end of a rigid, cylindrical electrode body made of plastic an internal electrolyte solution, typically NaF and NaCl, and an internal reference electrode complete the construction (Fig. 2.6). At room temperature, LaFg is a pure F"-ion conductor. 

The europium-doped inorganic—organic hybrid samples were prepared as follows the Eu(fod)3.2Tl20 was dissolved in dry ethanol and to the solution obtained was added to the insoluble hybrid. 

Europium-doped LS samples were prepared as follows the Eu(fod)3 was dissolved in dried ethanol and to the resulting solution the insoluble LS was added. The suspension was stirred for 30 min and the solvent evaporated. The resulting powder was dried at 60°C under vacuum in a stove. Eu(fbd)3 and LS were mixed in stoichiometric amounts to produce samples with 1%, 5%, and 10% (m/m) of adsorbed complex. 

Figure 9-3. SEM image of cubic shape europium doped yttrium orthoborate particles.

The synthesis of europium-doped strontium carbodiimide, SrNCNrEu, was successfully accomplished by the solid-state reaction of Srl2, Eul2 CsCN, and CSN3. The crystal structure and purity of the a polymorph were checked by X-ray diffraction and infrared spectroscopy (Figure 3), and the results closely resemble those already found for the pure strontium compound. In particular, the average M—N bond distance arrives at 2.634(6) A, to be compared with d(Sr—N) = 2.644(4) A from a-SrNCN. ... 

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