Influence of vinyltriethoxysilane concentration on structural and luminescent characteristics of cerium doped yttrium based silicate phosphors

Cerium doped yttrium silicates phosphors (YSO:Ce) were prepared by gel combustion using vinyltriethoxysilane (VTEOS) as silicon sources along with aspartic acid as fuel and yttrium-cerium nitrate as oxidizer. The study presents the influence of VTEOS amount in the synthesis mixture on the structural and luminescent characteristics of silicate phosphors. The understanding of precursor׳s decomposition was achieved on the basis of thermal analysis in association with gas evolved analysis. XRD, FTIR and XPS were used to reveal the structural changes that occur with VTEOS molar amount variation from 1 to 3 mol. It was found that the main crystalline phase was X2-Y2SiO5. The luminescent characteristics of phosphors were measured at room and low temperature (10-300 K) based on emission and excitation spectra. Under UV excitation, YSO:Ce exhibits blue emission due to electron transition in Ce3+ from 5d level to the ground state levels (2F5/2, 2F7/2). The emission intensity increases from 70% to 120% along with VTEOS amount, explained by the improvements in structural homogeneity. Incorporation of cerium in different sites (Ce1 and Ce2) is discussed based on PL and PLE spectra measured at low temperature (10 K).