In situ preparation and luminescence properties of CaWO₄ and CaWO₄:Ln (Ln=Eu³⁺, Tb³⁺) nanoparticles and transparent CaWO₄:Ln/PMMA nanocomposites

CaWO₄ and CaWO₄:Ln (Ln=Eu³⁺, Tb³⁺) nanoparticles were prepared by reverse microemulsion with a functional monomer, methyl methacrylate (MMA), as the oil phase. Then CaWO₄/poly (methyl methacrylate) (PMMA) and CaWO₄:Ln/PMMA nanocomposites were obtained via polymerization of the MMA monomer. The nanoparticles and nanocomposites have been well characterized by X-rey diffraction (XRD), low- and high-resolution transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDX), UV–vis transmission spectra, photoluminescence excitation and emission spectra. The well-crystallized CaWO₄, CaWO₄:Eu³⁺, and CaWO₄:Tb³⁺ nanoparticles are all spindle-like with average diameter of 100 nm at the center and average length of 270 nm. They show the characteristic emission of WO₄^2- (¹T₂-¹A₁), Eu³⁺ (⁵D₀–⁷F_J, J = 1–4, with ⁵D₀–⁷F₂ red emission at 615 nm as the strongest one) and Tb³⁺ (⁵D₄–⁷F_J, J = 6–3, with ⁵D₄–⁷F₅ green emission at 547 nm as the strongest one), respectively. The obtained solid CaWO₄:Eu³⁺/PMMA(EuNC), CaWO₄:Tb³⁺/PMMA(TbNC) and CaWO₄/PMMA(CaNC) nanocomposites are highly transparent in the visible spectral range and exhibit strong red, green and blue photoluminescence upon UV excitation, due to the incorporation of luminescent CaWO₄:Eu³⁺, CaWO₄:Tb³⁺ and CaWO₄ nanoparticles, respectively. These nanocomposites can be potentially used as illumination and display materials.