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Temperature Dependent Luminescence of Yellow‐Emitting α‐Sialon:Eu 2+ Oxynitride Phosphors for White Light‐Emitting Diodes
Author(s) -
Liu Lihong,
Xie RongJun,
Hirosaki Naoto,
Takeda Takashi,
Li Jiguang,
Sun Xudong
Publication year - 2009
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2009.03275.x
Subject(s) - sialon , phosphor , luminescence , activator (genetics) , materials science , quenching (fluorescence) , analytical chemistry (journal) , mineralogy , chemistry , fluorescence , ceramic , metallurgy , optics , optoelectronics , organic chemistry , physics , biochemistry , gene
Yellow‐emitting α‐sialon:Eu 2+ phosphors have been reported as interesting down‐conversion luminescent materials in white LEDs. In this work, the thermal quenching of α‐sialon:Eu 2+ with the compositions of M val+ ( m /val+) Si 12−( m + n ) Al m + n O n N 16− n (M=Ca, Mg, Lu) is studied by investigating the effects of chemical composition, activator concentration, and substitution cation on the temperature‐dependent luminescence. The chemical composition of α‐sialon:Eu 2+ was varied in a wide range (0.5≤ m ≤2.0, 1≤ n ≤1.8). It shows that the m value significantly affects the thermal quenching of α‐sialon, whereas the n value hardly does. This difference is ascribed to the obvious lattice expansion and the increase of absolute activator concentration as m increases. The thermal quenching increases with increasing the Eu 2+ concentration, which is due to enhanced Stokes shift. The type of substitution cation also has an influence on thermal quenching. Among the substitution cations in this work, Lu‐α‐sialon:Eu 2+ exhibits largest thermal quenching. Photoionization is considered as the mechanism for the thermal quenching of Lu‐α‐sialon: Eu 2+ .