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8478522 
Journal Article 
Ce3+ -Activated gamma-Ca2SiO4 and Other Olivine-Type ABXO(4) Phosphors for Solid-State Lighting 
Kalaji, Ali; Mikami, M; Cheetham, AK; , 
2014 
Yes 
Chemistry of Materials
ISSN: 0897-4756
EISSN: 1520-5002 
AMER CHEMICAL SOC 
WASHINGTON 
3966-3975 
WOS:000338806700015 
Yellow-emitting phosphors activated by Ce3+ are key components of white light-emitting diodes (LEDs) based on the blue (Ga,In)N LED. In these phosphors, the electronic environment around Ce3+ determines its photoluminescence wavelengths. Placing Ce3+ in octahedral sites in oxides can potentially lead to yellow or orange phosphors that can compete with the important commercial phosphor, Y3Al5O12:Ce. However, there are very few examples of such materials. In this article, we explore the photoluminescent behavior of Ce3+ in oxides with the olivine structure, whereby two distorted octahedral doping sites exist. We demonstrate that the promising new yellow phosphor y-Ca2SiO4:Ce requires a second dopant, Al, to avoid the formation of the undesired /3 polymorph. Our results indicate that the yellow emission is indirectly caused by the complex polymorphism of Ca2SiO4, particularly the low temperature formation of the y-phase. The dramatic shift in emission from yellow to light-blue when this phosphor is heated to 800 degrees C is explained in terms of the redistribution of Ce3+ in the lattice. A similar effect is observed when Si4+ is substituted by Gel". The light-blue emission of Ca2GeO4:Ce,A(1) is reported as well as the photoluminescent properties of the Ca2(Ge,S004:Ce,A1 solid solution.