SiO2/TiO2/Ag multilayered microspheres: Preparation, characterization, and enhanced infrared radiation property

Abstract

SiO2/TiO2/Ag core–shell multilayered microspheres were successfully synthesized by the combination of anatase of TiO2 modification on the surfaces of SiO2 spheres and subsequent Ag nanoparticles deposition and Ag shell growth with face-centered cubic (fcc) Ag. The composites were characterized by TEM, FT-IR, UV–vis, Raman spectroscopy and XRD, respectively. The infrared emissivity values during 8–14μm wavelengths of the composites were measured. The results revealed that TiO2 thin layers with the thickness of ∼10nm were coated onto the SiO2 spheres of ∼220nm in diameter. The thickness of the TiO2 layers was controlled by varying the amount of TBOT precursor. Homogeneous Ag nanoparticles of ∼20nm in size were successfully deposited by ultrasound on the surfaces of SiO2/TiO2 composites, followed by complete covering of Ag shell. The infrared emissivity value of the SiO2/TiO2 composites was decreased than that of pure SiO2. Moreover, the introduction of the Ag brought the remarkably lower infrared emissivity value of the SiO2/TiO2/Ag multilayered microspheres with the lowest value down to 0.424. Strong chemical effects in the interface of SiO2/TiO2 core–shell composites and high reflection performance of the metal Ag are two decisive factors for the improved infrared radiation performance of the SiO2/TiO2/Ag multilayered microspheres.