The luminescence decay curves of Eu

3+

:Y

2

O

3

nanocrystals with different diameters and same doped concentration were studied.The surface states act as quenching centers in the luminescence

so the measured lifetimes decrease along with the decreases of the particle size.And the luminescence decay curves of nanocrystals with the same diameter and different doped concentrations were also studied.The measured lifetimes decrease with the increasing of the doped concentration.In high dopant concentration

energy transfer between luminescent ions is caused by exchange interaction.The energy transfer between dopant ions accelerates the quenching through the surface states.The surface state and size confinement bring the different influences to energy transfer in nanocrystals with different size nanocrystals.It is obtained that nanocrystals have much higher quenching concentration than that of bulk material and the quenching concentration of 40um nanoparticles is higher than that of 5nm nanopaticles.The reason of the increasing of quenching concentration is analyzed.Impurity and dislocation may act as bulk quenching center.If the same raw materials were used in preparing samples

concentrations of impurity are identical despite the sizes of the nanocrystals.But the configuration of dislocation is influenced by the nanocrystals size.Dislocation in nanocrystals is not stable below a certain critical size.Nanocrystal has hardly any dislocation when its size is smaller than the critical size.Dislocation density of nanocrystals would be much lower than that of bulk material.The number of bulk quenching center is very small.It has been found that nanocrystals have higher quenching concentration than bulk material.However

experimental evidence indicates that the relationship between quenching concentration and the particle size is not a monotonic function.This is because that surface state effect and size confinement effect bring opposite influences to the energy transfers in nanocrystals.So if a appropriate size of nanocrystals is selected and the surface of nanocrystals are decorated

the nanocrystals doped luminescence material

which has high photoluminescence efficiency and high quenching concentration should be produced.