Eu3+ doped yttrium oxysulfide nanocrystals – crystallite size and luminescence transition(s)

Nanocrystals of yttrium oxysulfide doped with trivalent europium has been synthesized using a two step sol–gel polymer thermolysis method employing urea formaldehyde resin in the presence of ethylene diamine tetra acetic acid as chelating agent. In this synthesis, marginal tunability in crystallite size (φ = 7–15 nm) was achieved by varying the concentration of reactants and organic precursors. In this nanocrystalline system, various luminescence transitions, in particular 5D0 → 7F2 transition of Eu3+ shows moderate (∼ 60%) lifetime shortening which can be explained by considering possible increase in non-radiative rate (τnr) and also possible modification in optical electronegativity induced by surface states of the crystallites.