Rare earth oxysulfide phosphor is a class of important luminescent materials. Because of their excellent properties

they have been applied extensively in fluorescent materials

X-ray phosphors

long afterglow phosphors

upconversion materials

and so on. So

rare earth oxysulfide phosphors are drawing more and more attention in recent years. Rare earth oxysulfide phosphors are usually produced by traditional solid-state reactions. In solid-state reactions

high reaction temperature

long heating time

and a special protective atmosphere are required to obtain a pure crystal phase. Therefore

producing agglomerated particles of irregular shape by solid-state reactions is unavoidable. Another disadvantage is the destruction of phosphor material during grounding and milling. The destruction results in the greatly decreasing of luminescence efficiency of the phosphors. In our present work

La

2

O

2

S:Eu

a red-emitting phosphor was rapidly synthesized by microwave radiation method for the first time. The synthesized phosphors were investigated respectively by XRD

SEM and fluorescence spectroscopy. The results show that La

2

O

2

S:Eu phosphors possess hexagonal crystal structure

which is similar to that of pure La

2

O

2

S. The particles of La

2

O

2

S:Eu phosphors are unregular in shape

dispersing well. The mean particle size is about 2 m. The excitation spectrum of La

2

O

2

S:Eu is a wide band in the range of 200~450 nm. It results from the charge transfer states of Eu

3+

ions (Eu

3+

-O

2-

Eu

3+

-S

2-

). Anarrow peak at 472 nm can been found in the excitation spectrum attributed to the f-f transition absorption of Eu

3+

ions. The emission spectrum shows that La

2

O

2

S:Eu has a series of narrow emission peaks located at 512

539

556

583

596

617 and 627 nm. These emission peaks are attributed to Eu

3+

ions transition from

5

D

J

(

J

=0

1

2) to

7

F

J

(

J

=0

1

2

3

4). All the emission peaks are ascribed as follows

617 nm and 627 nm (

5

D

0

7

F

2

)

596 nm (

5

D

0

7

F

1

)

583 nm (

5

D

0

7

F

0

)

556 nm(

5

D

1

7

F

2

)

539

(

5

D

2

7

F

4

)

512 nm (

5

D

2

7

F

3

). With the increase of Eu

3+

mol fraction from 2% to 10%

the main excitation peak shows an obvious shift to the long wavelength from 348 nm to 365 nm; the emission peaks in blue and green region become weaken gradually relative to the main emission peak at 627 nm. Therefore the red emitting at 627 nm become stronger gradually. When the content of Eu is 8%

the red emitting becomes the strongest. Further increasing the molar ratio of Eu

3+

the intensity of main emission peak will decrease.