RE borate glass is a kind of potentially valuble luminescence material. The luminescence intensities of borate glasses with various concentrations of RE ions (Ce

3+

Sm

3+

Eu

3+

Gd

3+

Tb

3+

Dy

3+

) have been measured.In case of Ce

3+

Sm

3+

Dy

3+

. it is found that the emission intensities of glasses decrease if the RE ion concentration exceeds a specific value. It may be explained by cross relaxation for Sm

3+

and Dy

3+

. Sometimes non-radiation losses occur due to interaction between two RE ions

when the Ce

3+

concentration increases

the probability of energy transfer exceeds that of emission.The concentration quenching occurs at 1mol% of cerium due to Ce

3+

-Ce

3+

transfer followed by transport to killer sites. However in case of Eu

3+

Gd

3+

Tb

3+

concentration quenching was not found in this work. Maybe their critical quenching concentrations are larger than 3mol%.It was found energy transfer from. Pr

3+

Gd

3+

Sm

3+

to Eu

3+

and from Ce

3+

Gd

3+

Dy

3+

to Tb

3+

. The energy transfer from Gd

3+

to Tb

3+

and Eu

3+

was discussed in detail.Fig.3 shows the excitation spectra of Gd

3+

and Tb

3+

in doubly and singly doped borate glasses. The excitation spectrum of 312nm emission of Gd

3+

in borate glass shows 237nm band which correspond to

8

S

7/2

-

6

I transition (see Fig. 3-c). The excitation spectrum of 542nm emission of Tb

3+

in doubly doped (Tb

3+

+Gd

3+

) borate glass also consists of 273nm band which is heightened with increase of Gd

3+

concentration. This indicates that the excitation energy may be transferred from Gd

3+

to Tb

3+

.The efficiency and probabilities of energy transfer from Gd

3+

to Tb

3+

was estimate from emission intensities of Gd

3+

+Tb

3+

doped borate glass. According to the concentration dependence of energy transfer probabilities

we belive that the interaction between Gd

3+

and Tb

3+

is dipole-dipole interaction