Cerium pentaphosphate

CeP

5

O

14

is an ultrafast scintillator

which has a uv-emission band with an extremely short lifetime (about r

1

=12nsec.).Ce

3+

in cerium pentaphosphate has a broad uv-absorption band.So it can be used as sensitization ion. We have investigated a new crystalline luminescence material

CeP

5

O

14

:Mn

which can emit strong green-yellow light.A series of CeP

5

O

14

:Mn crystals were grown from phosphoric acid by the evaporation solution method. The usual experimental conditions are as follows:The manganese carbonate (purity:A.R.) is added to a gold crucible

in which G.R.-grade commercial orthophosphoric acid

H

3

PO

4

containing 15% by weight of water

is filled. As the manganese carbonate has been dissolved completly

the cerium oxide (purity:99.99%) is added into the solution.This mixture is heated in the crucible to about 250℃ and kept for about two days until the excess water has evaporated and the cerium oxide has dissolved. Subsequently the temperature is raised to about 550℃. After a week the crucible is taken out and the mother liquor is poured out of the crucible. The crystals are rinsed in hot water repeatedly. The CeP

5

O

14

:Mn crystals

colourless or with a pale yellow colour could be obtained.CeP

5

O

14

:Mn crystal compositions were determined by chemical analysis. No obvious change in Ce% content was observed when Mn% content was small. The structure of CeP

5

O

14

:Mn crystal was determined.When the content of Mn% in the crystal was low

the crystal structure of CeP

5

O

14

:Mn was the same as that of CeP

5

O

14

both belong to the monoclinic system

space group P21/c. Some lattice parameters of CeP

5

O

14

:Mn were calculated by a computer. The results are shown in table 1.The CeP

5

O

14

:Mn crystals emit strong green-yellow light when they were excited by 254nm ultraviolet light.The luminescence intensity increases with the increase of Mn% content. CeP

5

O

14

emits ultraviolet light and no luminescence of LaP

5

O

14

:Mn was observed.The results indicate the energy transfer from Ce

3+

to Mn

2+

exists.The absorption spectra show that CeP

5

O

14

has a strong absorption peak in the wavelength range of 255-320nm

LaP

5

O

14

:Mn has a weak peak at 290nm

and when CeP

5

O

14

is doped with manganese

the absorption peaks move toward the shorter wavelength side and a split of absorption peak were observed (fig.1).The excitation spectra of CeP

5

O

14

:Mn has been measured. The excitation peak of CeP

5

O

14

:Mn is the same as that of CeP

5

O

14

. The intensity of the strongest peak shown at 302nm decreases as the content of Mn% increases.The emission spectra of CeP

5

O

14

:Mn under excitation of 302nm show three groups of emission peaks at about 332

545

and 665nm. But CeP

5

O

14

has only one group peaking at about 332nm

so the other two groups peaking at 545 and 665nm are considered as emission of manganese ion.An interesting phenomenon was observed

as the content of Mn% was increased

the emission intensity at 545nm was increased

while that at 685nm was decreased. As shown in fig

4 and fig

5