Boric anhydride (B

2

O

3

) is a compound rather strong in acidity. At given temperatures

it can be co-soluble with the metal oxides of alkaline earth

alkali

molybdenum or vanadium

and yeild glassy or solid solutions. In this experiment

europium yttrium boratovanadate phosphor has been synthesized using yttrium boratovanadate as the host and europium as the activator. Photoluminescence behaviour has been studied.Appropriate experimental conditions for synthesizing the phosphor and optimal compositions for luminescence

(Y

0.94

Eu

0.06

) (V

0.69

B

0.01

)O

3.7

were found out. Adding small amount of rare-earth impurity

e.g.Gd

2

O

3

Sm

2

O

3

has little effect on or a slight enhancement of the europium luminescence under 365nm excitation. However

adding luminescent compounds such as Zn

2

GeO

4

. GeO

2

:Mn and SrLaBO

4

:Pb has markedly enhanced the europium luminescence. This is ascribed to the overlap of the emission bands of the added compounds with the absorption bands of europium. Adding Bi

3+

to the phosphor results in a great increase of the luminescence intensity. The excitation band of Bi

3+

-containing sample is broadened with peak shifted toward the longer wavelength side. The emission band of Bi

3+

peaking at 539nm can be seen in the emssion spectrum (fig. 3). The increase of the luminescence intensity is therefore attributed to the summing up of the Bi

3+

and Eu

3+

emission.The peak of the excitation band of Eu

3+

is at 326nm

corresponding to the excitation transition of the cluster VO

4

3-

and the band may overlap with excitation band of the charge transfer state of Eu (fig. 1

2). Besides

lines at 383

396

418

467 and 539nm in this band correspond to the excitation from

7

F

0

to

5

D

4

5

L

6

5

D

3

5

D

2

5

D

1

.The emission spectrum of Eu is composed of the lines at 594

610

616

619

699 and 705nm

the most intense ones are at 616 and 619nm

corresponding to the transition from

5

D

0

to

7

F

2

.By the investigations of the emission spectra of the sample under different temperatures

it is pointed out that the optimal temperature for luminescence is about 350℃ (fig.5). The effect of temperature on luminescence depends on the energy absorption by the host and Eu

as well as on the increased efficiency of energy transfer from the host to Eu. Below 350℃

the luminescence intensity increases rapidly with the increasing temperature; above this temperature

the decrease follows. It is supposed that Eu can be efficiently excited by ultraviolet light to the charge transfer state(4

f7

2p

-1

). With the increase of temperature

the charge transfer state lowers down and the absorption band shifts toward longer wavelength side

nearer to the excitation wavelength 324nm of VO

4

3-

; whereas the lowered energy level gets nearer to the 4f excited state

thus increase the probability of relaxation to the 4f excited state (the number of phonons corresponding to the energy difference between the two states decreases) resulting in the increase of luminescence intensity. Again

the most important factor is the broadening of the excitation and emission band of VO

4

3-

with the increase of temperature

thus increase the overlapping part of the two bands and increase the energy transfer efficiency. Similarly

the absorption band of Eu is also broadaned with the increase of temperature and so increase its overlap with the emission band of VO

4

3-

and increase the efficiency of energy transfer from VO

4

3-

to Eu

3+

resulting in the marked in'crease of lumineicence intensity. However

when the temperature outruns 350℃

thermal quenching begins to play a marked role in the luminescence and causes the luminescence intensity to decrease gradually.