Y

2

O

3

:

Ln

nanocrystals with different

Ln

3+

(

Ln

=Eu or Tb) doping concentrations and average sizes were prepared by chemical self-combustion. And the bulk materials of corresponding doping concentrations were obtained by annealing at high temperature. The emission spectra

excitation spectra and X-ray diffraction spectra of Y

2

O

3

:

Ln

nanocrystals and bulk materials were measured. The research indicated that under the effect of quantum confinement effect and surface effect

the Y

2

O

3

:Eu charge transfer band red-shifted clearly while the particle size decreased. Furthermore

the charge transfer band of the small size particles (8 nm) clearly broadened towards the long wavelength

this was attributed to the increase of the amount of Eu

3+

ions existing in low crystallization degree environment close to the surface. The study also indicated that the shape of excitation peaks (bands) corresponding to the 4f5d transition absorption of Tb

3+

in the excitation spectra of Y

2

O

3

:Tb nanocrystals changed a lot with the variety of the particle size. This is because that the Tb

3+

ions exist in two very different local environments:the low crystallization degree environment close to the surface and the high crystallization degree environment inner the particles. The absorption peaks of 4f5d transition were different in the two environments. The Tb

3+

ions ratio in the two environments changs with the variety of the particle size. So the intensity of corresponding excitation peaks (bands) changed and the shapes of the excitation spectra changed. By comparing the excitation spectra of different doping concentrations

it can be found that with the increase of Tb

3+

(or Eu

3+

) concentrations

the relative strength of the Y

2

O

3

exciton transition absorption excitation peak to the 4f5d transition (or charge transfer band) excitation peak decreased. The excitation efficiency of Y

2

O

3

exciton absorption band is very low when the doping concentrations of the luminescent centers were higher. But the excitation efficiency of Y

2

O

3

exciton absorption band increased when the doping concentrations were quite low.