The cerium-doped yttrium aluminum garnet(YAG:Ce) phosphor is commonly used in white LED as the luminescence converter.The thermal quenching property of YAG:Ce

3+

phosphor has important effects on the luminous efficiency

photo-chromic parameters and reliability ofwhiteLED athigh temperature.In this paper

Y

3-x

Ce

x

AlO

12

(and Y

2.93-y

Ce

0.07

M

y

Al

5

O

12

(

M

=Lu

Gd) phosphorswere prepared by the high tempe-rature solidstate reaction method.The temperature-dependent photoluminescence properties of these phos-phorswere investigated under the excitation of 460 nm blue light.It is observed that the temperature has great influences on the photoluminescence properties of YAG:Ce

3+

phosphors.With the temperature increasing

the relative brightness is decreased and the emission band shifts toward the red.For Y

2.93

Al

5

O

12

:Ce

0.07

the relative brightness at 150℃ is only 89% comparedwith thatat the room temperature

and the emission band shifts toward the red for about 10 nm.The Ce

3+

concentration has no obvious effecton the thermalquenching properties of YAG:Ce

3+

.For Ludoped YAG:Ce

3+

phosphors

the blue shift of the emission spectra is observed because of the introduction ofLu3+ion which has a smaller ion radius than that of Y

3+

ion.The emission peak shifts to the blue for about 15 nm as the concentration ofLu increases from 0 to 2.5.It is also noted that the Lu

3+

substitution for Y

3+

has an improvementon the thermalquenching property of YAG:Ce

3+

phosphor.The relative brightness of Y

2.93-y

Ce

0.07

Lu

y

Al

5

O

12

phosphors with different y values retains above 94% at 150℃ compared with that at the room temperature.The relative brightness of Lu

2.93

Al

5

O

12

:Ce

0.07

phosphor changes very little at elevated temperature

and falls only by 3% at 150℃ comparedwith its brightness at room temperature.TheGd substitution for Y

3+

can shift the emission spectra of YAG:Ce

3+

toward longerwavelength

at the expense ofdeteriorating the thermal quenching property.The red shiftof the emission peak with Gd-doped YAG:Ce

3+

phosphorswasmeasured up to 35 nm with the concentration of Gd increasing from 0 to 2.5%.At the same time

the emission intensity is falling down rapidly.With the concentration of Gd increasing

the thermalquenching properties of Gd-doped YAG:Ce

3+

phosphors are alsoworsened.At 150℃

the Y

2.93-y

Gd

y

Al

5

O

12

:Ce

0.07

phosphorwithy 0.5 only can retain 78% of its luminance atroom tempera-ture

lower than that of undoped YAG:Ce

3+

+phosphor.The relative brightness of Y

2.93-y

Ce

0.07

M

y

Al

5

O

12

:Ce

0.07

phosphor withy 2.5 is below 90% when temperature is above 60℃

and drop to 30% at 150℃