Luminescent properties of Sm(III) ions in Ln2(WO4)3 entrapped in silica xerogel

Silica xerogel doped with Ln2−xSmx(WO4)3, where Ln = Gd(III) or La(III), were prepared by the sol–gel procedure. The parameter x in the formula was changed in the 0.02–2.0 range. Absorption and photoluminescence of a new kind of red light phosphors with emitting Sm3+ ions were studied at room temperature. In this type of luminescent material, prepared by the sol–gel method, samarium(III) ions exhibit enhanced luminescence emission owing to excitation energy transfer from WO 4 2 - groups to Sm3+ ions in the Ln2−xSmx(WO4)3 salt. The enhancement is particularly large for Gd2−xSmx(WO4)3, where x = 0.1, and La2−xSmx(WO4)3, x = 0.2, compounds entrapped in a silica xerogel. However, the La–Sm system exhibits higher emission intensity than the Gd–Sm material. The emission intensity of both the materials was additionally improved by removing O–H oscillators by the thermal treatment.