Synthesis and fluorescence properties of CdTe:Eu ³⁺ nanocrystals and core–shell SiO ₂ ‐coated CdTe:Eu ³⁺ nanospheres

Abstract

Abstract Eu 3+ doped‐CdTe (CdTe:Eu 3+ ) nanocrystals were prepared via a facile hydrothermal method, and Eu 3+ was successfully incorporated into the crystal lattice of CdTe and measured by X‐ray powder diffraction (XRD), transmission electron microscopy (TEM), ultraviolet–visible (UV–Vis) absorption spectroscopy and fluorescence emission. The CdTe:Eu 3+ nanocrystals still have a cubic crystal structure, and the corresponding XRD peaks of CdTe:Eu 3+ nanocrystals shift to larger angles compared with those of pure CdTe. The CdTe:Eu 3+ nanocrystals are monodisperse and the particles size is about 2–4 nm. Compared with pure CdTe, the CdTe:Eu 3+ nanocrystals have larger band gap and thus exhibit blueshift in the emission spectra, which could be accounted for by the energy transfer between Eu 3+ and CdTe. To enhance the stability and functionality of CdTe:Eu 3+ nanocrystals, the CdTe:Eu 3+ nanocrystals were coated with SiO 2 and the core–shell SiO 2 ‐coated CdTe:Eu 3+ nanocrystals (CdTe:Eu 3+ @SiO 2 ) were prepared via micro‐emulsion method. TEM results show that CdTe:Eu 3+ nanocrystals are uniformly dispersed in the shell, and CdTe:Eu 3+ @SiO 2 nanospheres are uniformly spherical with an average diameter of about 75 nm. The fluorescence emission of CdTe:Eu 3+ @SiO 2 (567 nm) shows a blueshift compared with that of CdTe:Eu 3+ nanocrystals (632 nm), possibly because of altered surface properties after SiO 2 coating. CdTe:Eu 3+ and CdTe:Eu 3+ @SiO 2 with tunable photoluminescence are potentially useful in fabricating optical and bioimaging devices.