Studies on Y2SiO5:Ce phosphors prepared by gel combustion using new fuels

Abstract

Cerium activated yttrium silicate (Y2SiO5:Ce) phosphors were prepared by combustion, using yttrium– cerium nitrate as oxidizer, aspartic or glutamic acid as fuel and TEOS as source of silicon. In this study, aspartic and glutamic acid are used for the first time for the synthesis of Y2SiO5:Ce phosphors. The fuels molar amount was varied from 0.5 mol to 1.5 mol in order to reveal the thermal behavior of intermediary products (gels and ashes) same as the structural and luminescent characteristics of final products (phosphors). According to thermal analysis correlated with FTIR and XPS investigations, the combustion process occurs differently depending on the fuel amount; unreacted nitrate compounds have been identified in fuel lean conditions and carbonate based compounds along with organic residue in rich fuel conditions. The conversion to well crystallized silicates was revealed by changes of FTIR vibration bands and confirmed by XRD measurements. Based on luminescent spectra, aspartic acid is a better fuel than glutamic acid. A positive effect on the luminescence have been observed for samples fired in air due to complete remove of organic residue. The best luminescence was obtained for combustions with 0.75 mol aspartic acid and 1.25 mol glutamic respectively, fired at 1400 C for 4 h in air atmosphere.