JSI - Synthesis of Materials K8

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Head of Department 

Prof. Dr. Darko Makovec
darko.makovec@ijs.si 
Telephone: +386 1 477 35 79

 

 

Secretary

Bernarda An┼żelak
bernarda.anzelak@ijs.si
Telephone: +386 1 477 33 23

Materials for which the properties are determined by incorporated magnetic nanoparticles

 

Magnetic nanoparticles are of great interest for various applications in the fields of engineering and biomedicine. Their magnetic properties are mostly governed by size effects and the intrinsic properties of the material. Two distinct limiting sizes that govern magnetic properties exist. The critical size, below which the nanoparticles are in a single-domain state, and the critical size below which the nanoparticles are in the superparamagnetic state. From the materials synthesis point of view, the latter is of major importance. Soft magnetic materials, such as spinel ferrites (iron oxides, magnetite and maghemite), are superparamagnetic when their size is reduced below approximately 20 nm. Superparamagnetic nanoparticles do not exhibit a remanent magnetization. In the absence of a magnetic field they behave as “nonmagnetic”. Because the magnetic attractive force between nanoparticles is absent, colloidal suspensions of superparamagnetic nanoparticles, so-called magnetic fluids, can be prepared. Magnetic fluids are important for various technological applications, such as sealing, heat transfer, and damping. Colloidal suspensions of nanoparticles are also the starting materials for tuning nanoparticles’ surface properties, the so-called functionalization of nanoparticles, and for the synthesis of new complex materials. The tuning of surface properties is of key importance for biomedical applications of nanoparticles. Larger superparamagnetic nanoparticles that are suitable for applications in magnetic separation can be prepared by the controlled agglomeration of nanoparticles in suspensions. Layers on solid substrates can be prepared by the deposition of nanoparticles from colloidal suspensions. The control of the nanoparticles’ morphology, suspension properties and forces that are acting on the nanoparticles during their deposition enables the preparation of layers with anisotropic and/or coupled functional properties. Multifunctional nanocomposite particles are prepared by combining magnetic nanoparticles with other functional materials. The preparation of colloidal suspensions is also a basic step for dispersing nanoparticles in solid matrixes, such as silica or polymers. Colloidal suspensions of single-domain nanoparticles are seldom desired. Their preparation is challenging due to the strong magnetic attraction between the nanoparticles.

 

Therefore, the synthesis of complex materials requires mastering the synthesis of magnetic nanoparticles and their colloidal suspensions, i.e.,  magnetic fluids.

 

An important part of the research is also devoted to the influence of the finite size of nanoparticles on their structural properties and the influence of the nanostructuring of complex materials on their useful properties.

JSI - Synthesis of Materials K8