Ce

Tb activated LaPO

4

(G

P

) is one of the high effective rare earth green luminescent materials

which has been applied in three basic color fluorescent lamp in the last ten years. In present work

G

P

has been synthesized

analysed and compared with pratical green phosphor CeMgA111O19;Tb(G

A1

) on excitation and emission spectra. It can be seen on emission spectra that the 543nm (

5

D

4

-

7

F

5

) halfwidth of Gp is 3nm smaller than G

A1

and its intensity is lower. The intensities for longer wavelengths 584nm (

5

D

4

-

7

F

4

) and 620nm (

5

D

4

-

7

F

3

) are stronger than that of G

A1

however the y value of which is smaller than G

A1

Therefore

in order to get the same color temperature

when G

P

is selected for the green component

the amount of red phosphor can be deduced.There are some differences in excitation spectra. One is that the measured brightness of G

P

is 7% higher than G

A1

when excited under 254nm. The other is the excitation spectra bands sited after 310nm of Gp are increased

excited intensity of which at 313nm is three times higher than G

A1

. In addition

intensities of G

P

at 351

369 and 377nm are 2-3 times increased than G

A1

. When rare earth three basic phosphors are used for lamps

the luminescence caused by the secondary mercury lines (313

365nm) must be considered. According to the relative intensities of 313nm and 365nm line in low pressure mercury lamp and relative excited intensities of 313nm and 365nm in G

A1

the brightness increased by 313nm and 365nm excitation is calculated. The increasing factor for G

P

is about 1%

but for G

A1

it is only 0.1%. Thus

it is shown that G

P

is of more benefit to the increase of luminous flux in lamp fabrication.This paper also deals with the effects of La

Ce proportion on emission and excitation spectra of G

P

. It is indicated that emission and excitation spectra of G

P

are all the same when La

Ce proportions are different (La is changed from 0 to 0.58

Ce is varied from 0.8 to 0.22). The above fact means that the function of Ce is not only sentisizer but also a part of host which plays the same role as La. In the case of lack of Ce

the emission spectra of G

P

still shows the Tb luminescent lines

but the brightness of which is obviously decreased.