Red emission of Eu(III) ions doped gadolinium or lanthanum tungstate entrapped in silica xerogel

The europium(III) novel phosphors were synthesised and then entrapped in silica based transparent inorganic material prepared by the sol–gel process. The photoluminescence properties of novel Eu(III) phosphors were studied by means of steady-state and time-resolved techniques. In particular, energy transfer from WO42- to Eu(III) ions was observed and demonstrated by their enhanced luminescence intensity. Energy transfer occurred particularly effective for xerogels doped with Gd2−xEux(WO4)3, where x = 1.2, and La2−xEux(WO4)3, x = 0.8. Especially interesting seems strong red acceptor emission observed upon excitation at 240 nm (donor excitation). Therefore these materials seem promising as red phosphors. Additionally, the emission intensity of the materials was improved by reducing concentration of such quenchers as water molecules and OH groups by the thermal treatment.