Enhanced luminescence in Ln³⁺-doped Y₂WO₆ (Sm, Eu, Dy) 3D microstructures through Gd³⁺ codoping

Microstructures of Y2WO6 were prepared by applying a hydrothermal synthesis in the presence of sodium dodecyl sulfate (SDS) surfactant, after which the materials were heat-treated at a temperature of 1100 °C. When prepared at pH 3, the spherical 3D microstructures were built from nanosized particles. Raising the pH gave materials built from differently shaped building blocks, which influenced the final architecture. These materials, similarly to other previously investigated and reported rare-earth tungstate materials, were found to show very interesting luminescence properties. However, quantum yield (QY) values have scarcely been reported for such materials. In this work, a detailed study of the photoluminescence characteristics, decay times, and quantum yields of Y2WO6 doped with Sm(3+), Eu(3+), and Dy(3+) is presented. When doped with different concentrations of Ln(3+) ions, the luminescence properties of the samples changed. The 2.5% Dy:Y2WO6 sample gave white-light emission and showed a QY of 17%. For the optimal lanthanide-ion concentrations, the systems were codoped with 2% and 10% Gd(3+) ions to test the possible enhancement of luminescence through energy transfer from W-O and/or Gd(3+) to Ln(3+). The Eu(3+),Gd(3+)-codoped system showed QYs as high as 79%. The Sm,Gd-codoped system showed the highest enhancement of QY. After incorporation of Gd(3+) ions, the 2.5% Sm_10% Gd:Y2WO6 materials showed a QY approximately 2.4 times larger than that of the 2.5% Sm:Y 2WO6 material.