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Preface xi In 1996, a new lighting device was proposed by Nichia Chemical Co., based on a blue InGaN LED chip coated with a yellow-emitting phosphor, cerium-doped yttrium aluminum garnet (Y2.9Ce0.1Al5O12, YAG:Ce3+). The lighting device proved to have numerous advantages over traditional incan- descent and fluorescent lamps, such as small size, long lifetime, robustness, fast switching, and high efficiency. Phosphor materials such YAG:Ce3+ play an unquestionable role for achieving high color-quality white emission in LED technology. However, conventional phosphors used in fluorescent lighting or displays are not good candidates for LED lighting because they are optimized for excitation at the wavelength of a mercury discharge tube at 254 nm, while InGaN chips emit in the blue. The aim of this review is to provide clues for the design of efficient lanthanide-based LED phosphors. After a description of the principles of LED lighting and phosphor require- ments, the structures and luminescence properties of LED phosphors are pre- sented. The classification of phosphors is primarily based on the chemical composition such as oxide, nitride, and sulfide; on the emission color such as yellow, green, and red; and, finally, on the actual chemical formula. This is because it is convenient to understand the phosphor characteristics on the basis of the nature of chemical bonding, which controls the energy of electronic tran- sitions, in the solid state. In practical applications for white light LED devices, powder technology is important so that the chapter describes synthesis methods of phosphor particles including morphology control. Implementation of phos- phors in LED lighting devices is dealt with in the last section, as well as recent progresses in remote phosphors and wafer-level packaging. CHAPTER 279: REE MINERALOGY AND RESOURCES M. Hoshino*, K. Sanematsu*, and Y. Watanabe† *Mineral Resource Research Group, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan. E-mail: hoshino-m@aist.go.jp †Akita University, Mining Museum of Akita University, Akita, JapanPDF Image | HANDBOOK ON THE PHYSICS AND CHEMISTRY OF RARE EARTHS
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