Core-shell structured nanoparticles are garnering attention because these nanoparticles are expected to have a wide range of applications. The objective of the present study is to improve the coating efficiency of gold shell formed on the surface of silica nanoparticles for SiO₂@Au core-shell structure. For the efficient coating of gold shell, we attempt an in-situ synthesis method such that the nuclei of the gold nanoparticles are generated and grown on the surface of silica nanoparticles. This method can effectively form a gold shell as compared to the conventional method of attaching gold nanoparticles to silica particles. It is considered possible to form a dense gold shell because the problems caused by electrostatic repulsion between the gold nanoparticles in the conventional method are eliminated.

Cost-effective functional phosphor nanoparticles are prepared by introducing low-cost SiO₂ spheres to rareearth phosphor (YVO₄:Eu³⁺, YVO₄:Er³⁺, and YVO₄:Nd³⁺) shells using a sol-gel synthetic method. These functional nanoparticles are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and general photoluminescence spectra. The SiO₂ sphere occupying the interior of the conventional phosphor is advantageous in significantly reducing the cost of expensive rare-earth phosphor nanoparticles. The sol-gel process facilitates the core–shell structure formation; the rare-earth shell phosphor has strong interactions with chelating agents on the surfaces of SiO₂ nanoparticles and thus forms layers of several nanometers in thickness. The photoluminescence wavelength is simply tuned by replacing the active materials of Eu³⁺, Er³⁺, and Nd³⁺. Moreover, the photoluminescent properties of the core–shell nanoparticles can be optimized by manipulating the specific contents of active materials in the phosphors. Our simple approach substitutes low-cost SiO₂ for expensive rare-earth-based phosphor materials to realize cost-effective phosphor nanoparticles for various applications.

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• Enhanced Energy-Transfer Properties in Core-Shell Photoluminescent Nanoparticles Using Mesoporous SiO₂ Intermediate Layers
  Woo Hyeong Sim, Seyun Kim, Weon Ho Shin, Hyung Mo Jeong
  Korean Journal of Metals and Materials.2020; 58(2): 137.     CrossRef