Several rare earth activators (Dy 3 + , Sm 3 + , Eu 3 + ) doped nanocrystalline and microcrystalline Sr 2 Gd x Y 7 . 9 - x (SiO 4 ) 6 O 2 are synthetized by sol-gel method. The luminescence and the energy transfer properties from Gd 3 + to Ln 3 + are studied. The results show that the energy transfer efficiency from Gd 3 + to Ln 3 + is in the sequence Sm 3 + <Eu 3 + <Dy 3 + in the nanocrystals, in the microcrystals the sequence is different, and compared to the counter microcrystals, the value of energy transfer efficiency in the nanocrystals from Gd 3 + to Ln 3 + is lower.