Fluorescent Lamp Phosphor Particles

In this application showing how the log-normal plot can be utilized, we can readily see that the mechanicaT separation of fines has created a new particle distribution with d 2 = 2 p. Even the Aralue of differs from 

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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. 

Fluorescent lamps are manufactured by squirting a suspension of phosphor particles in an ethyl cellulose lacquer upon the inner surface of a vertical glass tube. Once the lacquer drains off, a film of peuticles is formed. The lacquer is then burned off, leaving a layer of phosphor particles. Electrodes are sealed on the tube is evacuated Hg and inert gas is added and the lamp ends are added to finish the lamp. Lamp brightness and lifetime are dependent upon the particle size distribution of the phosphor particles. The number of small particles is critical since they are low in brightness output... 

In fluorescent lamps, a layer of phosphors is applied to the inside of a glass tube by means of a suspension of particles, i.e.- the halophosphate phosphor having a composition of Ca5F,Cl(P04)3 Mn " (plus minor... 

The fluorescent lamp is basically a low pressure mercury discharge lamp with a layer of phosphor particles on the inside surface of the glass tube, as shown in 6.6.6., presented on the next page. 

Deposition-precipitation with urea has been also used to prepare Eu doped-YjOj/silica materials (39), which find application not in catalysis, but in the field of phosphor emitting in fluorescent lamps and cathode ray tubes. The method has been applied for depositing yttria (9.7 wt %) doped with Eu (0.30 wt %) from a mixture of nitrates heated at 80°C in the presence of urea and silica for 90 min. After thermal treatment at 900°C, YjOj particles are 12 nm large, coated by a silicate, and after thermal treatment at 1000°C, the a-YjSijO, phase forms. It exhibits interesting luminescent properties, and the authors conclude that this method of preparation is more promising than the sol-gel method. 

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