Cactus-like double-shell structured SiO2@TiO2 microspheres: Fabrication, electrorheological performances and microwave absorption

The cactus-like double-shell structured SiO 2 @TiO 2 microspheres (CDS SiO 2 @TiO 2 microspheres) with high dielectric properties were successfully fabricated and utilized as high-performance electrorheological (ER) fluids and microwave absorbing materials. The SiO 2 nanospheres with average diameters of 190   nm were synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS), and used as the core for the first coating layer of TiO 2 achieved by sol-gel method. The final cactus-like TiO 2 layer was prepared via a hydrothermal method. The morphology of the resultant samples was characterized via transmission electron microscopy (TEM), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). This novel CDS SiO 2 @TiO 2 microspheres based suspension exhibited improved ER properties compared to conventional bare SiO 2 spheres.