Structural and photoluminescence properties of Tb-doped CaMoO4 nanoparticles with sequential surface coatings

• 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.

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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