Multicolor luminescence of PbWO₄: RE³⁺ (Sm³⁺, Dy³⁺, Eu³⁺ and Tb³⁺) phosphor prepared via hydrothermal method

Purely crystalline PbWO₄: RE³⁺(Sm³⁺, Dy³⁺, Eu³⁺ and Tb³⁺) were prepared via hydrothermal method at 150 °C. X-ray diffraction studies of all the doped samples were in accordance with the tetragonal scheelite type structure of PbWO₄ phase with no extra phase. Vibrational modes were also studied using FT-IR and Raman spectroscopy. All the excitation spectra of the samples showed strong and broad band with a maxima at around 320 nm due to charge transfer transitions within WO₄ ²⁻groups and series of sharp excitation peaks that can be assigned to typical intra-4f transitions of rare-earth ions. Under 320 nm UV light excitation, the photoluminescence spectra of RE³⁺ doped PbWO₄ showed characteristic emission lines of the rare-earth dopant ions which can be attributed to the efficient charge transfer from WO₄ ²⁻ groups to the rare-earth ions. From the CIE calculation, these prepared samples showed multi-color luminescence in the same host at a single excitation wavelength by altering the dopant ions in the host matrix.