结构控制荧光粉热特性机制研究  

Investigation on Thermal Stability Properties of Phosphors by Crystal Structure

作　　者：王筱姗 陈韦廷 刘如熹[1] 

机构地区：[1]台湾大学化学研究所,台北10617

出　　处：《中国稀土学报》2014年第1期16-23,共8页Journal of the Chinese Society of Rare Earths

基　　金：台湾国科会基金资助项目(NSC101-M-002-014-MY3)

摘　　要：紫外光-蓝光发光二极管激发之高效率红色荧光粉为生活中重要照明来源,尤其须具极佳本质特性,例如化学与热稳定性佳。相较于氧化物荧光粉,氮化物荧光粉的发光通常较红位移且热/化学稳定性较佳,乃因其共价性较大,例如:Sr2Si5N8:Eu2+与CaAlSiN3:Eu2+。阳离子取代通常可用于调控其光学特性与热稳定性之最适化,但相关的研究与机制尚未被清楚地了解,故本研究乃利用邻近阳离子取代可系统性地调控CaAlSiN3:Eu2+系列之热特性。当三价阳离子取代于其中的Ca2+格位时,其热稳定性随之变差。反之,以一价阳离子取代时,则热稳定性提升。由荧光寿命之衰减光谱亦可得知阳离子取代的光谱特性变化。邻近阳离子取代与调控其中Al3+/Si4+的组成作为电荷平衡,使活化剂离子Eu2+可选择性地取代于特定Ca2+格位中。当三价阳离子取代时,其Eu2+离子位于邻近Al3+/Si4+平均之阴离子团配位中,然而当一价阳离子取代时,其将位于Si-rich之配位环境中,故其发光光谱特性可受阳离子取代而调控。此机制将可被广泛应用于荧光材料,藉此有效地调控其光谱特性。Highly efficient red phosphors with superior intrinsic properties that are excited by ultraviolet or blue light-emitting diodes are important white light sources for our daily life. Nitride-based phosphors, Eu2 ＋ such as SrzSisN8 ：Eu^2＋ and CaA1SiN3 ： , are com- monly more red-shifted in photolumineseence and have better thermal/chemical stability than oxides. Cation substitutions are usually performed to optimize photo- luminescence and thermal quenching behavior. However, the underlying mechanisms are unclear in most cases. Here we showed that neighboring-cation substi- tution systematieally controlled temperature-dependent Eu2 ＋ photoluminescence behavior in CaAlSiN3： lat- tice. Trivalent cation substitution at the Ca^2＋ site degraded the photoluminescence in high temperature environments but achieved better thermal stability when the substituted cation turned monovalent. The neigh- boring-cation control of lifetime decay was also observed. A remote control effect that guides Eu^2＋ acti- vators in selective Ca2＋ sites was proposed for neigh- boring-cation substitution while the compositional Si^4＋/Al^3＋ ratio adjusted to the valence of Mn＋ （n = 1 -3） cation. In the remote control effect, the Eu^2＋ activators are surrounded with nitride anions which neighbor with M^3＋ -dominant and Si^4＋/Al^3＋ -equiva- lent coordination when M is trivalent, but shift to the site where surrounded nitride anions neighbor with M^＋ -dominant and Si-rich coordination when M is monovalent. This mechanism can efficiently tune optical properties, especially thermal stability, and could be general to luminescent materials, which are sensitive to valence variation in local environments.

关 键 词：荧光粉 红光 热特性 稀土 

分 类 号：O482.31[理学—固体物理]