LaPO

4

:Ce

Tb was an important green luminescence material used in tricolour fluorescent lamp.It could replace the(Ce

Tb) MgAl

11

O

19

phosphor used in the China.The main synthesis method of the phosphor was the high temperature solid state method.The phosphor had a great particle size.It must be milled when it was used.This way not only increased production cost

but also influenced on luminescence intensity.(La

Ca

Tb)PO

4

was prepared by coprecipitation of a rare earth nitrate solution with diammonium hydrogen phosphate as precipitation agent while adding little surfactant and controlling the conditions of the reaction.The green-emitting phosphor LaPO

4

:Ce

Tb used in fluorescent lamps was prepared by it as the precursors.The most suitable technological conditions were obtained.RE(NO

3

)

3

and(NH

4

)

2

HPO

4

were si multaneously added at the same rate in the experiment.The concentrations of RE(NO

3

)

3

and(NH

4

)

2

HPO

4

should be the same in order to ensure a uniform precipitation.The suitable concentration of the feed liquid is 0.2mol/L.The suitable reaction temperature was controlled to be 30~40℃ in the experiment.The crystal size of(La

Ce

Tb) PO

4

in precipitation and its property of filtre were improved by adding a little surfacetant.The precipitation and mother liquid were aged for a period with a pH value of 7 usually.The suitable aging time is 1-2h

and the suitable aging temperature was determined to be 50-60℃.The most suitable calcination temperature of the phosphor is 900℃ and calcination time is 1h under the carbon-reducing atmosphere.The partical size of the LaPO

4

:Ce

Tb fluorescent powder prepared in present experiment was mea-sured by a laser granularity meter:D

50

=4.34μm.The particle is fine and the granularity displays a narrow normal distribution which can meet the needs of fluorescent lamp fabrication.The X-ray diffraction spec-trum clearly shows that the fluorescent powder has a phosphatic monoclinic monazete structure without any impurity phase and the structure didn't change after adding H

3

BO

3

.The phosphor LaPO

4

:Ce

Tb was mea-sured by PMS-3 chromatic detector

and its luminescent chromatic coordinate parameters are:x=0.347 4

y=0.758 4

the colour rending index is

R

a

=22.5.The phosphor had high luminescence intensity which was equal to that of the(Ce

Tb) MgAl

11

O

19

phosphor in market.The phosphor LaPO

4

:Ce

Tb prepared by coprecipitation had higher luminescence lightness

finer particle and lower calcinations temperature than that prepared by the high temperature solid state method.The coprecipitation method become possible synthesis ways of non-grinding green fluorescent powder of phosphate.