GdB

3

O

6

was synthesized by the solid state reaction at high temperatures.The UV excitation and emission spectra were recorded by a Hitachi M850 fluorescent spectrometer at room temperature.Because the part of

6

G

J

energy levels of Gd

3+

are below 50000cm

-1

so these

6

G

J

energy levels of Gd

3+

could be measured by UV excitation.The observation of photon cascade emission of the Gd

3+

ion in GdB

3

O

6

under

8

S

7/2

→

6

G

J

ultraviolet excitation(202nm) was reported.In this host lattice

the lowest energy state of the Gd

3+

4f5d excited configuration is located above the

6

G

J

state.The

6

G

J

→

6

P

J

and

6

G

J

→

6

I

J

transitions are responsible for the first photon emission.The second photon emission originates from the

6

P

J

→

8

S

7/2

transitions.In the GdB

3

O

6

host

the energy difference ΔE between the

6

D

9/2

and

6

I

11/2

(about 2900cm

-1

)

and that between

6

I

7/2

and

6

P

J

(about 3900cm

-1

) are smaller

the multiphonon relaxation rate exceeds remarkably the radiative decay rate

so the absence of emission from the

6

D

J

and

6

I

J

states to the ground state

8

S

7/2

is attributed to the efficient multiphonon

6

D

J

→

6

I

J

and

6

I

J

→

6

P

J

relaxation.