ARTICLE IN PRESS Available online at www.sciencedirect.com ScienceDirect ADVANCED ELSEVIER MATERIALS www..com/locate/stam Review Silicon-based oxynitride and nitride phosphors for white LEDs-A review Rong-Jun Xie*,Naoto Hirosaki Nimride Partlcle Group.Nano Ceramies Center,Natonal Istitute for Materlals Sclence.Naik Tsukuba.Ibarak 305-0044.Japa Abstract mn o-aee) Nitride:Phosphor Luminescence:White LEDs Sialo Contents atrodiction of nitride ence of silicon-based oxynitride and nitride phosphors. ellow-emittin phosphors 。。。 。。 。。。 ons of oxynitride and nitride phosphors in white LEDs emowedgmens............................................................................ Please csrie.Xi N.Hirosaki,Sci.Technol.Adv.Mater.(2007doi:am5Science and Technology of Advanced Materials ] (]]]]) ]]]–]]] Review Silicon-based oxynitride and nitride phosphors for white LEDs—A review Rong-Jun Xie, Naoto Hirosaki Nitride Particle Group, Nano Ceramics Center, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan Received 11 June 2007; received in revised form 25 July 2007; accepted 27 August 2007 Abstract As a novel class of inorganic phosphors, oxynitride and nitride luminescent materials have received considerable attention because of their potential applications in solid-state lightings and displays. In this review we focus on recent developments in the preparation, crystal structure, luminescence and applications of silicon-based oxynitride and nitride phosphors for white light-emitting diodes (LEDs). The structures of silicon-based oxynitrides and nitrides (i.e., nitridosilicates, nitridoaluminosilicates, oxonitridosilicates, oxonitridoaluminosilicates, and sialons) are generally built up of networks of crosslinking SiN4 tetrahedra. This is anticipated to significantly lower the excited state of the 5d electrons of doped rare-earth elements due to large crystal-field splitting and a strong nephelauxetic effect. This enables the silicon-based oxynitride and nitride phosphors to have a broad excitation band extending from the ultraviolet to visible-light range, and thus strongly absorb blue-to-green light. The structural versatility of oxynitride and nitride phosphors makes it possible to attain all the emission colors of blue, green, yellow, and red; thus, they are suitable for use in white LEDs. This novel class of phosphors has demonstrated its superior suitability for use in white LEDs and can be used in bichromatic or multichromatic LEDs with excellent properties of high luminous efficacy, high chromatic stability, a wide range of white light with adjustable correlated color temperatures (CCTs), and brilliant color-rendering properties. r 2007 NIMS and Elsevier Ltd. All rights reserved. Keywords: Oxynitride; Nitride; Phosphor; Luminescence; White LEDs; Sialon Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Classification and crystal chemistry of nitride compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Structure and luminescence of silicon-based oxynitride and nitride phosphors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Blue-emitting phosphors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2. Green-emitting phosphors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3. Yellow-emitting phosphors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.4. Red-emitting phosphors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4. Synthesis of silicon-based oxynitride and nitride phosphors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1. Solid-state reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.2. Gas-reduction nitridation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.3. Carbothermal reduction and nitridation (CRN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5. Applications of oxynitride and nitride phosphors in white LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 ARTICLE IN PRESS www.elsevier.com/locate/stam 1468-6996/$ - see front matter r 2007 NIMS and Elsevier Ltd. All rights reserved. doi:10.1016/j.stam.2007.08.005 Corresponding author. Tel.: +81 29 860 4312; fax: +81 29 851 3613. E-mail address: Xie.Rong-Jun@nims.go.jp (R.-J. Xie). Please cite this article as: R.-J. Xie, N. Hirosaki, Sci. Technol. Adv. Mater. (2007), doi:10.1016/j.stam.2007.08.005