adviser : ming-shyong tsai date : 2012/03/21

Reporter : Che-Wei KuoAdviser : Ming-Shyong TsaiDate : 2012/03/21

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Fine-sized Y3Al5O12:Ce phosphor powders prepared by spray pyrolysis from the spray solution with barium fluoride flux

Outline Introduction

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 2







Conclusions 3

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.

Fig 1. (a) LED (b) YAG doped with Ce3+

(a)

(b)

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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.

Methods of producing YAG powders

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Conclusions 6

Materials

Aluminum nitrate Al(NO3)3 9H‧ 2O Yttrium nitrate Y(NO3)3 6H‧ 2O

Cerium nitrate Ce(NO3)3 6H‧ 2O

Barium fluoride BaF2

Deionized water

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Methods

Al(NO3)3 9H‧ 2O Y(NO3)3 6H‧ 2O Ce(NO3)3 6H‧ 2O

Barium fluoride (BaF2)

Dissolved in deionized water

Spray pyrolysis

Precursor powders

Calcination

YAG:Ce

XRD

SEM

PL

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Conclusions 9







Conclusions 10

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.

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Thanks for your attention

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adviser : ming-shyong tsai date : 2012/03/21

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