Improvement of luminescence intensity of material by core-shell formation or dispersion in another matrix was reported in literature. In this direction, we have prepared Y2O3: Eu3+ particles dispersed in SiO2. However, their luminescence intensities are less than Y2O3: Eu3+ due to non-radiative process arising from association of amorphous silica and Si-O-H. Variation of luminescence intensity is described in terms of site symmetry, heat-treatment effect and surrounding medium. Intensity of electric dipole transition is more than that of magnetic dipole transition for samples heated up to 1100 degrees C. For higher heated sample at 1300 degrees C, the opposite effect is found. This is explained on the formation of new triclinic phase alpha-Y2Si2O7. (C) 2011 Elsevier B. V. All rights reserved.