A series of La

4

(P

2

O

7

)

3

:Ce

Gd

Tb phosphors have been prepared by precipitation from aqueous solution and subsequent ignition.XRD measurements confirm that the products are pure phase La

4

(P

2

O

7

)

3

. Excitation and emission spectra

relative brightness and cerium luminescence lifetime of these phosphors have been obtained.It is shown that in the crystalline lattice of La

4

(P

2

O

7

)

3

the spectra of Ce and Gd overlap with each other

rendering certain interaction to occur between them and hence bringing about some increase of brightness of (La

0.64

Ce

0.3

Gd

0.06

)

4

(P

2

O

7

)

3

as compared to either (La

0.7

Ce

0.3

)

4

(P

2

O

7

)

3

or(La

0.94

Gd

0.06

)

4

(P

2

O

7

)

3

.On the other hand

Ce effectively sensitizes Tb

enhancing the Tb emission considerably.However

the coexislance of Gd and Tb gives rise to competitive absorption and individual emission

rendering a slight decrease of the brightness of(La

0.80

Gd

0.06

Tb

0.14

)

4

(P

2

O

7

)

3

as compared to that of singly doped(La

0.86

Tb

0.14

)

4

(P

2

O

7

)

3

.Consequently in the case of codoping of Ce

Gd

and Tb

the emission is also weakened.