Triphosphors

Fig. 8. The emission spectmm of a triphosphor blend where A is BaMg2Al g02y B, CeMgAl O c, and C, Y2O2 Eu ". ...

The cost of rare-earth phosphors in fluorescent lamps is often reduced by double coating the lamps. The rare-earth phosphor blend is coated over a base layer of the inexpensive halophosphate phosphor (Fig. 9). In this configuration it absorbs a disproportionate amount of the uv discharge. For example, about 70% of the uv is absorbed in the inner coating with only one layer of triphosphor particles on the inside. 

Fig. 9. A modem fluorescent lamp coating including a conductive layer of Sn02 F, then a protective coating of finely divided alumina, followed by the inexpensive halophosphate phosphor, and finally a thin layer of the triphosphor rare-earth blend.

The Red-Emitting Triphosphor. Eu + -activated Y2O2 phosphor is the universally used red-emitting triphosphor for lamps. The emission spectmm of this phosphor is almost ideal being dominated by one strong line at 611 nm. This SDg — transition is called hypersensitive because if, for... 

CeMgAljjOjgi. The first triphosphor lamps were made possible with the discovery of this phosphor and the class of aluminate-based... 

Orthophosphoric acid containing three acid OH groups in the molecule offers many opportunities for the realization of surface-active molecular structures. But phosphoric acid also possesses the ability to form polyacids in an widespread manner. Pyrophophoric acid and triphosphoric acid are substances that have been known for a long time. This presents further possibilities for interesting synthesis. 

The ability of phosphoric acid to form condensed molecules is an additional effect. Examples of this kind of acid are pyrophosphoric acid, H4P207 structure (1), and triphosphoric acid, H5P3O 0 structure (2) ... 

The product, H4 P2 O7, is pyrophosphoric acid. A second condensation leads to triphosphoric acid ... 

Further condensation of phosphate groups leads to the polyphosphoric acids, which contain several phosphate units. The acids themselves are not particularly useful, but salts of some of these acids are used extensively. Triphosphoric acid, also known as tripolyphosphoric acid, H5P3O10, can be considered as a product of the reaction... 

Although Fischer2 stated that D-glucosone is not fermented by yeast it has recently been reported157 to be fermented by yeast extracts fortified with adenosine-5-triphosphoric acid and codehydrogenase I. 

A triokinase, isolated from liver, phosphorylates both D-glycerose and DL-glycerose, at the same rate, in the presence of adenosine-5-triphosphoric acid (ATP), and phosphorylates dihydroxyacetone at approximately half the rate.77-78... 

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