Luminescence enhancement in composite material: CaWO4:Tb3+ nanocrystals incorporated into silica xerogel

• Composite luminescent material consisting of CaWO4:Tb nanoparticles embedded in silica matrix was prepared.
• Energy transfer from SiO2 matrix and WO42− groups to Tb3+ ions was observed.
• The nanoparticles capped with silica exhibited enabling luminescence enhancement.

Calcium tungstate CaWO4 nanoparticles doped with Tb3+ of 20 nm in average size were prepared by sonochemical method. The crystallites were immobilized in a silica matrix by the sol–gel method. The matrix in the CaWO4:Tb3+@SiO2 composite material plays two roles. First of all it provides a good coverage of the nanoparticle defected surface and it prevents the nanoparticles from agglomeration. The nanoparticles capped with silica are characterized by energy transfer from WO42− group to Tb3+ thus enabling luminescence enhancement of the latter ions. The composite luminescent material was analyzed by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED) and luminescence techniques. CaWO4:Tb3+@SiO2 exhibits higher emission intensity than CaWO4:Tb3+ in the nanopowder form.

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