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 WO42- 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.