Y1-xInGe2O7:Mx3+(M = Bi, Sm, Er, Dy)之合成與光致發光特性研究

Synthesis and photoluminescence properties of Y1-xInGe2O7 doped with Mx3+ ions (M = Bi, Sm, Er, Dy)

戴品綸(Pin-Lun Dai)

指導教授 ： 張益新

國立虎尾科技大學/電機資訊學院/光電與材料科技研究所/碩士(2009年)

摘要

本研究主要是以行星式球磨固態反應法來製備鍺酸鹽YInGe2O7螢光粉體，並添加不同濃度之稀土金屬離子Bi3+、Sm3+、Er3+與Dy3+來作為發光中心，以探討其掺雜濃度對螢光粉體之晶體結構與光致發光特性的影響，期許能藉此開發出可用之新穎發光材料並應用於新世代白光LED上。
由XRD分析結果顯示，所合成之Y1-xInGe2O7:Mx3+(M = Bi, Sm, Er, Dy)螢光粉體，在煆燒溫度1300℃持溫10小時的條件下，皆能獲得單一相的Monoclinic YInGe2O7之結晶結構，可形成完全的固溶體。而在Sm3+、Er3+與Dy3+離子所掺雜之螢光粉體中，其粉體之表面形態則並不會因掺雜濃度之多寡而有所影響，但在掺雜具有類似助熔劑效果的Bi3+ 離子之作用下，其晶體之表面形態有明顯得到改善，且在微量的Bi3+離子掺雜下，確實能有效提升螢光粉體的結晶性。
掺雜Sm3+、Er3+與Dy3+離子所製備之螢光粉體在光學特性方面，由於電荷轉移吸收帶與晶格能隙重疊，兩者之間所發生的能量轉移使得電荷轉移吸收的能量無法有效轉移給稀土離子發光，所以只能由稀土離子的4f內層軌域躍遷來進行激發。且由衰減曲線的分析結果顯示其所有的發光皆呈現單一自然指數衰減行為，即表示在Y1-xInGe2O7:Mx3+( M = Sm, Er, Dy)螢光粉體中僅有單一發光機制的存在，爾後也皆因濃度淬滅效應的影響，致使衰減時間快速縮短。
在YInGe2O7:Bi3+螢光粉體之光致發光的分析結果則發現有來自YInGe2O7與YInGe2O7:Bi3+兩者螢光粉體之光學特性存在，此從衰減速率所呈現的非自然指數之衰減行為而得到證實。由於主體與活化劑離子之間，能量能夠有效的轉移，使得衰退時間被拉長，屬於長時間的發光。
另外於本研究所製備之螢光粉體在光色方面，已具備有藍光(YInGe2O7: Bi3+)、橘黃光(YInGe2O7:Sm3+)、綠光(YInGe2O7:Er3+)與近白光(YInGe2O7:Dy3+)，其激發波長則圍繞在302 ~ 404 nm之間，極具有應用於固態照明系統之可行性。

關鍵字

鍺酸鹽 ； 螢光粉體 ； 掺雜 ； 光致發光特性

並列摘要

In this study, YInGe2O7 germanate phosphors was selected as the host material, and doped with different concentrations of Mx3+ (M = Bi, Sm, Er, Dy) ions which were synthesized using a planetary ball mill solid-sate reaction and calcined at 1300℃ for 10 h in air. The phases, morphologies, and photoluminescence properties of the Y1-xInGe2O7:Mx3+ (M = Bi, Sm, Er, Dy) phosphors were then investigated.
The XRD results demonstrated that the crystal structure of Y1-xInGe2O7:M3+ phosphors can be attributed to the monoclinic YInGe2O7 phase, indicating that the Y3+ ions have been substituted by the M3+ ions in the lattice, and they can form solid solutions. The SEM results show that there are no obvious differences for surface morphology of Sm3+, Er3+ and Dy3+ doped the phosphors. But for Bi3+ ion doped, there are obvious improvements on the surface morphology of the YInGe2O7 powders because Bi2O3 acts as a flux reagent. Under a low Bi3+ ions concentration, it can enhance the crystallinity, luminescence properties of the YInGe2O7 phosphors.
Optical properties of M3+ (M = Sm, Er, Dy)-doped YInGe2O7 in detail, it is recognized that there are no efficient charge transfer state (CTS) band occurs in the phosphors. It is probably due to the CTS band overlaps with the absorption band of the host, and the CTS has less contribution to the excitation. All of the decay curves are attributed to a single exponential behavior, indicating that there is only a single decay mechanism. The concentration quenching effect occurred when the YInGe2O7 doped with high M3+ concentration leading the decay time to decrease.
For YInGe2O7 doped with Bi3+ ions, the PL results discovered that the decay curves represent a non-exponential behavior which indicates that the efficient energy transfer occurred between Bi3+ ions and host.
In this study, all synthesized phosphor powders can emit different colors by doping different kinds of activators, such as blue (YInGe2O7:Bi3+), orange-yellow (YInGe2O7:Sm3+), green (YInGe2O7:Er3+), near-white (YInGe2O7:Dy3+). The excitation wavelengths of the Y1-xInGe2O7:Mx3+(M = Bi, Sm, Er, Dy) phosphors are between 302 nm and 404 nm, which possesses a great potential for solid state lighting technology applications.

並列關鍵字

Yttrium indium germanate ； Phosphors ； Doped ； Photoluminescence properties

參考文獻

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