SiO2 effect on spectral and colorimetric properties of europium doped SrO2-MgO-xSiO2 (0.8 ≤ x ≤ 1.6) phosphor for white LEDs

Silicate phosphors with compositions 1.99 SrO2-1.0 MgO-xSiO(2)-0.01 Eu2O3 (x = 0.8, 1.0, 1.2, 1.4 and 1.6) were prepared in a reducing atmosphere via a solid state reaction. The resultant phosphors were examined by using x-ray diffraction and confirmed to be a mixture of monoclinic Sr2SiO4 and orthorhombic Mg-2(Si2O4). The scanning electron microscope images revealed that SiO2 content does not influence the morphology of the resultant phosphors. It was also observed that the excitation spectra are dependent on the monitored emission wavelength, and the emission spectra are dependent on the excitation wavelength and the SiO2 content. The energy transfer between Eu2+ ions occupying different Sr2+ sites was discussed. The colour coordinates for these phosphors are tunable based on both the excitation wavelength and the SiO2 content.