of the clusters that form a porous but space-filled shell around the template (Figure). Noninteracting metal-coated magnetic particles (SiO2/Au, Fe3O4/Au, NiO/Co,etc.) or coated semiconducting particles (PbS/CdS) are examples of such composite particle structures.
These structures can have applications in magnetic recording, as multilayered catalyst materials, or in drug delivery. In such applications of drug delivery systems , for which a biocompatible outer layer and a drug-containing inner core are necessary, the multilayered particle approach will be crucial. As an alternative
to colloidal templating, structures such as PbS-coated CdS nanocomposite particles (a few nanometers in diameter) may be synthesized by ion displacement in inverse microemulsions and could be useful in nonlinear optical applications. The observed large refractive nonlinearity in these nanocomposite particles may be attributed to the optical Stark effect and to strong interfacial and internanoparticle interactions.
Saithrhu R. Gonzalez C.