Military and Security Developments in China : U.S. Assessments, 2015

Ferrofluids, are strange materials that are part liquid, part magnet, and which solidify when exposed to magnetic fields. They consist of nanometer-sized magnetic particles dispersed in a nonmagnetic fluid such as water or kerosene and form a magnetic liquid. Ferrofluids are stable colloidal suspensions of nanosized magnetic materials in a suitable basefluid. They can be synthesized with or with out suitable surface coatings. The properties are greatly influenced by the grain size, carrier fluid chosen, and composition of the magnetic material and concentration of them in the fluid. Their flow and properties can be tuned with the application of an external magnetic field. The application potential of ferrofluids is enormous. They are important templates, from the fundamental physics point of view, to study the magnetism of non-interacting nanodomains. Also by tuning the concentration of this system, the effect of interaction also could be studied. They are also ideal templates for studying the quantum confinement effects in nanomagnetic materials. Hence, optically they are ideal systems as the grain size approaches the Bohr radius limit, high quantum confinement and induced blue shift can make them optically more transparent, and this confined exciton can assist in non-linear absorptions. As a random media, this can offer induced scattering which can make them good optical limiters owing to their high shelf life and stability against agglomeration.