title: On the origin of fine structure in the photoluminescence spectra of the β-sialon:Eu2+green phosphor.
abstract: The photoluminescence (PL) and PL excitation (PLE) spectra of Si6-zAlzOzN8-z(β-sialon):Eu2+phosphors with smallzvalues (z=0.025-0.24) were studied at room temperature and 6 K. The PL and PLE spectra exhibit fine structure with the PL lines being as sharp as 45-55 nm even at room temperature; this fine structure was enhanced by decreasing thezvalue. These results can be used for expanding the color gamut of liquid crystal displays, particularly in the blue-green region. From low-temperature measurements, the fine PLE structure was ascribed to discrete energy levels of7FJstates. The 4f65d excited states of Eu2+are considered to be localized near the 4f orbital. This is because the bonding of Eu2+with surrounding atoms is ionic rather than covalent. Lattice phonon absorptions were also observed in the PLE spectrum, revealing that the optically active Eu2+ions are located in the β-sialon crystal. The PL spectrum of the sample with the smallestzvalue (0.025) consists of a sharp zero-phonon line and lattice phonon replicas, which results in a sharp and asymmetric spectral shape.
authors.affiliation: Sharp Corporation Advanced Technology Research Laboratories, 2613-1, Ichinomoto-cho, Tenri, Nara, 632-8567, Japan; Sialon Unit, National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki, 305-0044, Japan.
authors.forename: Kohsei
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Sharp Corporation Advanced Technology Research Laboratories, 2613-1, Ichinomoto-cho, Tenri, Nara, 632-8567, Japan.
authors.forename: Ken-Ichi
authors.initials: KI
authors.lastname: Yoshimura
authors.affiliation: Sharp Corporation Advanced Technology Research Laboratories, 2613-1, Ichinomoto-cho, Tenri, Nara, 632-8567, Japan.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Harada
authors.affiliation: Sharp Corporation Advanced Technology Research Laboratories, 2613-1, Ichinomoto-cho, Tenri, Nara, 632-8567, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Tomomura
authors.affiliation: Sialon Unit, National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki, 305-0044, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Takeda
authors.affiliation: Sialon Unit, National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki, 305-0044, Japan.
authors.forename: Rong-Jun
authors.initials: RJ
authors.lastname: Xie
authors.affiliation: Sialon Unit, National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki, 305-0044, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Hirosaki
keywords: LCD; LED; phosphor; photoluminescence; sialon