Abstract
The crystal structure, surface chemistry and optical properties of Tb-doped CaMoO4 (CaMoO4:Tb) nanoparticles and the sequentially coated CaMoO4:Tb@CaMoO4 and CaMoO4:Tb@CaMoO4@SiO2 nanostructures have been characterized by X-ray diffraction (XRD), Thermo-gravimetric analysis (TGA), UV–vis absorption (UV–Vis), Fourier- transform infrared spectroscopy (FT-IR), Raman spectroscopy and Photoluminescence spectroscopy. The XRD results indicate that the obtained CaMoO4:Tb is sheelite tetragonal structure and well crystallized at 150 °C. The particle size increases from 21 to 48 nm by sequential coating of CaMoO4 and silica formation around the surface of core nanoparticles. These nanocrystals were well-dispersed in aqueous and non-aqueous solvents to form clear colloidal solutions. The colloidal solutions of three samples show well characteristic optical absorption band in UV/Visible region. The surface coating on core particles will significantly influence the structural and photoluminescence properties. The as-prepared core nanoparticles showed high photoluminescence as compared to surface coated core–shell nanoparticles because Tb3+ ion located at the particle surface. Absorption and luminescence spectroscopic studies have been examined for future application in the development of optical devices as well as optical bioprobes.
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•Low temperature synthesis process for preparation of core and core–shell nanoparticles.•Chemically, thermally stable core and core–shell nanoparticles highly dispersed in aqueous media.•Effect of surface coating on structural, optical and luminescence properties of CaMoO4;Tb nanoparticles.•Silica surface modified core–shell nanoparticles could be consider as alternative luminescent bioprobes.