Comparative study of the thermal diffusivity of SiO₂–Au nanoparticles in water base

Two SiO₂–Au nanoparticles were prepared. Silicon dioxide (SiO₂) structures with average size of 143 and 90 nm were synthesized using the sol–gel method. Gold (Au) nanoparticles of ~ 5 nm were deposited using the deposition–precipitation process on each dielectric platform. The concentration of silanol groups of SiO₂ spheres was obtained. The size and form of SiO₂, Au and SiO₂–Au nanoparticles were evaluated by transmission electron microscopy (TEM). The TEM micrographs confirmed the size and spherical form for SiO₂ and Au nanoparticles with high monodispersity, the decoration of SiO₂ spheres with metallic nanoparticles was also confirmed. The reflectance spectrum revealed a decreased of reflectivity around 516 nm for SiO₂–Au structures, the decrease of reflectance was associated with the presence of gold nanoparticles on dielectric spheres. The SiO₂–Au structures (at different mass 0.1–0.6 mg/ml) were dispersed in deionized water. Thermal diffusivity of SiO₂–Au particles in water was studied using the thermal lens (TL) spectroscopy. The results revealed an increase in thermal diffusivity as the SiO₂–Au concentration was increased. The thermal property was independent on the size of the SiO₂ spheres used.