Abstract
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Facile polyol and sol–gel Stober methods were used for synthesis of YF3:Tb+ (core), YF3:Tb+@LaF3 (core/shell) and YF3:Tb+@LaF3@SiO2 (core/shell/SiO2) nanoparticles (NPs). We investigated the crystalinity, morphology, surface chemistry, optical absorption and luminescence properties of these core and core/shell nanoparticles.
A simple polyol and sol–gel Stober process were employed for synthesis of YF3:Tb+ (core), YF3:Tb+@LaF3 (core/shell) and YF3:Tb+@LaF3@SiO2 (core/shell/SiO2) nanoparticles (NPs). The phase purity, crystalinity, morphology, optical and photoluminescence properties were investigated and discussed with the help of various analytical techniques including X-ray diffraction pattern, FE-transmission electron microscopy (TEM), FTIR, UV/vis absorption, energy band gap and emission spectra. XRD and FE-TEM studies indicate the formation of core/shell nanostructure and ∼10nm thick amorphous silica surface coating surrounding the core-NPs, which is also confirmed by FTIR spectral results. The surface modifications of core-NPs significantly affect the optical features in the form of energy band gap, which were correlated with particle size of the nanomaterials. The comparative emission spectral results show that after inert layer coating the luminescent core-NPs display stronger emission intensity in respect to core and silica coated core/shell/SiO2-NPs. The solubility character along with colloidal stability was improved after silica surface modification, whereas luminescent intensity was suppressed causing the surface functionalized with high energy silanol (Si-OH) molecules. These novel luminescent nanomaterials with enhanced emission intensity and excellent solubility in aqueous solvents would be potentially useful for fluorescence bioimaging/optical bio-probe etc.