Adviser : Ming-Shyong Tsai Date : 2012/03/21 Fine-sized Y3Al5O12:Ce phosphor powders prepared by spray pyrolysis from the spray solution with barium fluoride flux 以氟化鋇當作助燒結劑，藉由噴霧乾燥製備良好顆粒型態的YAG螢光粉 Reporter : Che-Wei Kuo Adviser : Ming-Shyong Tsai Date : 2012/03/21

Outline Introduction Experimental Results and Discussion Conclusions Applications of YAG Methods of producing YAG powders Experimental Materials Methods Results and Discussion Effect of spray pyrolysis with different ratio of BaF2 on synthsis reaction Effect of calcination with different ratio of BaF2 on synthsis reaction Composition of YAG: Ce phosphor Effect of BaF2 on luminescence property of powders Application of YAG:Ce in the white LED Conclusions

Outline Introduction Experimental Results and Discussion Conclusions Applications of YAG Methods of producing YAG powders Experimental Materials Methods Results and Discussion Effect of spray pyrolysis with different ratio of BaF2 on synthsis reaction Effect of calcination with different ratio of BaF2 on synthsis reaction Composition of YAG: Ce phosphor Effect of BaF2 on luminescence property of powders Application of YAG:Ce in the white LED Conclusions

Applications of YAG Yttrium aluminum garnet Y3Al5O12 (YAG) has a cubic garnet structure with variety of good optical properties as well as excellent chemical stability and creep resistance. YAG doped with other rare earth ions, such as Nd3+ and Ce3+, which can be solid-state lasers and LED in applications. (a) (b) 釔鋁石榴石是立方石榴石結構，具有良好的光學性質、化學穩定性以及抗潛變性。 摻雜Nd或Ce等稀土元素的YAG可以應用在固相雷射以及LED方面。 Fig 1. (a) LED (b) YAG doped with Ce3+

Methods of producing YAG powders Methods of synthesizing YAG powders , such as : Solid-state reaction method Solvothermal method Co-precipitation method Spray pyrolysis method Sol–gel method In previous literature, the flux addition has great influence on the ion diffusions and crystallinity in the solid-state reaction method. In this study, BaF2 flux was applied in the preparation of YAG:Ce phosphor powders by spray pyrolysis. 製備YAG的方法，除了一般常用的固相法以外，還有許多的合成方法，像是溶液熱法 共沉法 噴霧乾燥法 以及溶膠凝膠法等，本篇作者是以噴霧乾燥來製備YAG粉體。 在前人研究中發現在固相法中添加助燒結劑有助於離子間的擴散。 所以在本篇研究中，作者先以固相法添加氟化鋇製備噴霧溶液，藉由噴霧乾燥得到前驅粉體，接著進行高溫煅燒。

Outline Introduction Experimental Results and Discussion Conclusions Applications of YAG Methods of producing YAG powders Experimental Materials Methods Results and Discussion Effect of spray pyrolysis with different ratio of BaF2 on synthsis reaction Effect of calcination with different ratio of BaF2 on synthsis reaction Composition of YAG: Ce phosphor Effect of BaF2 on luminescence property of powders Application of YAG:Ce in the white LED Conclusions

Materials Aluminum nitrate Al(NO3)3‧9H2O Yttrium nitrate Y(NO3)3‧6H2O Cerium nitrate Ce(NO3)3‧6H2O Barium fluoride BaF2 Deionized water 硝酸鋁 硝酸釔 硝酸鈰 氟化鋇 去離子水

Methods YAG:Ce Barium fluoride (BaF2) Spray pyrolysis Al(NO3)3‧9H2O Y(NO3)3‧6H2O Ce(NO3)3‧6H2O Dissolved in deionized water Barium fluoride (BaF2) Spray pyrolysis XRD 將硝酸鋁 硝酸釔 硝酸鈰 加入去離子水中，接著加入氟化鋇製成噴霧溶液進行噴霧乾燥，得到的前驅粉體在進行1500度煅燒，最後就可以得到YAG螢光粉。 再將YAG螢光粉以XRD SEM PL 進行分析。本篇研究的煅燒溫度是根據作者先前研究中發現未添加助燒結劑的前驅粉體煅燒1500度才能形成純相的YAG粉體，所以本篇研究將煅燒溫度設定在1500度。 Precursor powders SEM Calcination PL YAG:Ce

Outline Introduction Experimental Results and Discussion Conclusions Applications of YAG Methods of producing YAG powders Experimental Materials Methods Results and Discussion Effect of spray pyrolysis with different ratio of BaF2 on synthsis reaction Effect of calcination with different ratio of BaF2 on synthsis reaction Composition of YAG: Ce phosphor Effect of BaF2 on luminescence property of powders Application of YAG:Ce in the white LED Conclusions

Outline Introduction Experimental Results and Discussion Conclusions Applications of YAG Methods of producing YAG powders Experimental Materials Methods Results and Discussion Effect of spray pyrolysis with different ratio of BaF2 on synthsis reaction Effect of calcination with different ratio of BaF2 on synthsis reaction Composition of YAG: Ce phosphor Effect of BaF2 on luminescence property of powders Application of YAG:Ce in the white LED Conclusions

Conclusions BaF2 flux added to the spray solution improved the morphological and optical characteristics of the YAG:Ce phosphor powders prepared by spray pyrolysis. The optimum amount of BaF2 flux added to prepare the YAG:Ce phosphor powders with regular morphology, fine size and high photoluminescence intensity was 9 wt.%. The maximum photoluminescence intensity of the YAG:Ce phosphor powders prepared with BaF2 flux was 144% of the powders without flux. 由SEM及PL圖可得知添加氟化鋇可以改善YAG螢光粉的顆粒形態以及光學性質。 當添加9%氟化鋇時，YAG具有較均一的顆粒型態 且螢光強度最高。 添加9%氟化鋇的YAG，螢光強度為未添加氟化鋇的YAG增加44%左右。

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