摻雜鉺離子於Gd2Ti2O7奈米粉體之上下轉換螢光特性研究

Up and Down-converted visible luminescence properties of Er3+ doped Gd2Ti2O7 nanocrystals

簡勇全(Chien, Yungchuan)

指導教授 ： 丁初稷

國立中正大學/工學院/光機電整合工程研究所/碩士(2012年)

摘要

本論文旨在研究改變不同的摻雜濃度與製程溫度來合成Er3+-doped Gd2Ti2O7粉末，並探討其螢光特性。
我們使用溶膠-凝膠法製備Er3+ (5, 10, 15, 20, 25 mol%)-doped Gd2Ti2O7奈米粉末，由實驗結果可得知其在Er3+ (10 mol%)–doped Gd2Ti2O7粉末在退火溫度超過800℃後，具有良好的結晶特性，其平均結晶顆粒大小隨著退火溫度的提高 (800~1200 ℃) 而從~70 nm增加到~180 nm。在980 nm紅外線雷射激發下，具有下與上轉換發光特性，其發光峰值分別為526 nm (2H11/2→4I15/2 )、547 nm (4S3/2→4I15/2)、660 nm (4F9/2→4I15/2)、1528 nm ( 4I13/2→4I15/2)。
而螢光放射波長在1528 nm的螢光生命週期，在Er3+摻雜濃度為(10 mol%) 時其衰減曲線為單一指數，但摻雜濃度為25 mol%時就稍為有一點偏離單一指數，此兩種摻雜濃度其上轉換機制皆為雙光子吸收，但是Er3+摻雜濃度較高 (10 mol%) 時，則因為短的鉺離子間距進而增強了上轉換能量轉移(energy-transfer up-conversion)及交互緩弛能量轉移 (energy-transfer cross- relaxation) 機制，所以得到較強的紅光。

關鍵字

上轉換

並列摘要

Er3+-doped Gd2Ti2O7 nanocrystals were fabricated by the sol-gel method. While the annealing temperature exceeds 800 °C, amorphous pyrochlore phase Er3+-doped Gd2Ti2O7 transfers to well-crystallized nanocrystals, and the average crystal size increases from ~70 to ~180 nm under 800 to 1200 °C/1 h annealing. The Er3+-doped Gd2Ti2O7 nanocrystals absorbing the 980 nm photons can produce the up-conversion (526, 547, and 660 nm; 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2, respectively) and Stokes luminescence (1528 nm; 4I13/2→4I15/2).
The IR PL decay curve is single-exponential for Er3+ (5 mol%)-doped Gd2Ti2O7 nanocrystals but slightly nonexponential for Er3+ (10 mol%)-doped Gd2Ti2O7 nanocrystals. For both 5 and 10 mol% Er3+ doping concentrations, the mechanism of up-converted green light is the two-photon excited-state absorption; however, much stronger intensity of red light relative to green light was observed for sample with 10 mol% Er3+ doping concentration. This phenomenon can be attributed to the reduced distance between Er3+-Er3+ ions, resulting in the enhancement of the energy-transfer up-conversion and cross-relaxation mechanisms.

並列關鍵字

upconversion

參考文獻

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