PDF Publication Title:
Text from PDF Page: 127
Rare Earth-Doped Phosphors for White LEDs Chapter 278 91 of a conventional LED with the phosphor dispersed in encapsulant. The phos- phor configuration in the latter work was not exactly the same as the so-called remote phosphor, but they indicated logically that separation of the phosphor from LED chips may improve light-conversion efficiency. Meanwhile, Leung (2014) pointed out that the increase in manufacturing cost of remote phosphor does not balance the gain of light output. He claimed that a downlight module with increased number of conventional white LED packages is cheaper than a downlight using a remote phosphor with the same output. There are many types of remote phosphor components. Typical ones are plate-shaped polycarbonate (Meneghini et al., 2013), polyethylene terephthal- ate (PET) (Huang et al., 2011a), or glass on which phosphors are applied with some binder. Phosphor-containing resins or glasses with a variety of shapes (plate, sphere, dome, etc.) have also been widely examined (Conner, 2012; Intematix, 2014; Schiel, 2012). A heat-resistant flexible fluorocarbon polymer-containing phosphor was also proposed as a remote phosphor (Huang et al., 2014). Many phosphor-containing glasses applicable to the remote-phosphor technology have also been studied. For instance, a composite glass (called “glass ceramics”) was produced by annealing a Ce-containing SiO2–Al2O3– Y2O3 glass (Fujita et al., 2008) leading to the deposition of crystals of YAG:Ce3+ phosphor. Another example is a phosphor-containing glass com- posite, which was obtained by heating a pressed mixture of glass powder and phosphors to a temperature above the glass transition temperature Tg (Fujita et al., 2013). The composite showed no degradation under 121°C, 95% relative humidity, and 2 atm (so-called highly accelerated stress test con- ditions, HAST) for 300 h. On the other hand, a silicone resin composite of the same condition showed apparent degradation. A last example is a phosphor- doped glass obtained by mixing a SiO2–Na2O–Al2O3–Ca2O glass powder with the phosphor (Tsai et al., 2013). The glass showed better stability in light output during the thermal aging test than a phosphor-mixed silicone resin. Electrophoretic deposition (EPD) is another process tested for application of phosphors on glass plates. The EPD process results in high particle densi- ties, but adhesion is usually low. To remedy this problem, a photochemical reaction was applied to the EPD process (Yum et al., 2003). A mixed solution of polyvinyl alcohol and ammonium dichromate ((NH4)2Cr2O7) was depos- ited on the phosphor layer made by EPD. Then, UV light was irradiated on it to improve the adhesion. Another way of improving the adhesion was pro- posed (Kitabatake et al., 2012). First, the surface of a phosphor powder was coated with SiO2 synthesized from TEOS. The coated phosphor was then deposited on a glass plate by EPD and a SiO2 sol was applied on the phosphor layer to fill up the space between phosphors. Finally, the plate was heated to 773 K to convert the SiO2 sol to SiO2 glass and fill up the space to improve the adhesion of phosphors.PDF Image | HANDBOOK ON THE PHYSICS AND CHEMISTRY OF RARE EARTHS
PDF Search Title:
HANDBOOK ON THE PHYSICS AND CHEMISTRY OF RARE EARTHSOriginal File Name Searched:
Chemistry-Rare-Earths-49.pdfDIY PDF Search: Google It | Yahoo | Bing
Sulfur Deposition on Carbon Nanofibers using Supercritical CO2 Sulfur Deposition on Carbon Nanofibers using Supercritical CO2. Gamma sulfur also known as mother of pearl sulfur and nacreous sulfur... More Info
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)