Preparation of porous SiO₂/Ni/TiO₂ multicoated microspheres responsive to electric and magnetic fields

A new type of multicoated porous SiO₂/Ni/TiO₂ composite particles with response to external electric and magnetic fields is presented in this paper. Porous silica spheres are used as cores instead of solid silica beads, which give a much lower density. Then, the magnetic nickel component is introduced to the porous silica core by using electroless plating, while the titania component is coated on the outerlayer. The morphology and structure of the particles were characterized by SEM, TEM, and XRD. The properties as well as the behavior of the synthesized multiplayer-coated spheres under external electric and magnetic fields have been investigated. The resulting composite particles showed good responses to the electric and magnetic fields by the reflection of being ordered into chains structures under an external electric or magnetic field, and the network patterns under the adjusted electric and magnetic fields superimposed perpendicularly. The introduction of a magnetic and dielectric function to porous silica particles may be of importance in various technologies.