Fabrication and luminescent properties of CaWO4:Ln3+ (Ln = Eu, Sm, Dy) nanocrystals

Scheelite CaWO4 doped with rare earth ions (Eu3+, Sm3+, Dy3+) were fabricated via a facile solvothermal process without further heat treatment, which used sodium oleate and oleylamine as capping reagent. The structure, morphology, and optical properties of the samples were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), high-resolution transmission electron microscope (HRTEM), X-ray photoelectron spectra (XPS), photoluminescence (PL) spectra and cathodoluminescence (CL). The XRD results reveal that all the doped samples are well assigned to the scheelite structure of the CaWO4 phase. Upon excitation by ultraviolet radiation, the CaWO4:Eu3+ phosphors show the characteristic 5D0–7F1–3 emission lines of Eu3+, and the CaWO4:Sm3+ phosphors demonstrate the characteristic 4G5/2–6H5/2–9/2 emission line of Sm3+, and the CaWO4:Dy3+ phosphors demonstrate the characteristic 4F9/2–6H13/2–15/2 emission line of Dy3+.