Projects / Programmes
Synthesis of magnetic nanoparticles for the microwave absorbers and magnetic fluids
| Code |
Science |
Field |
Subfield |
| 2.04.00 |
Engineering sciences and technologies |
Materials science and technology |
|
| Code |
Science |
Field |
| T153 |
Technological sciences |
Ceramic materials and powders |
synthesis of nanoparticles, ferrites, microvawe materials, nanocomposites, magnetic fluids
Researchers (16)
Organisations (2)
Abstract
The project is concerned with investigation, which will lead to the syntheses of nanoparticles of barium hexaferrite, one of technically most attractive magnetic materials, which can be applied in magnetic fluids and microwave absorbers. The syntheses route will be developed via the controlled hydrothermal process governed by the basic theory of crystallization, which strictly separates the nucleation from the particle growth process. The synthesized magnetic nanoparticles will be used to prepare magnetic nanocomposites for the absorption of electromagnetic radiation and for magnetic fluids.
Significance for science
In the project, ultrafine, superparamagnetic nanoparticles of barium hexaferrite were hydrothermally synthesized together with their stable suspensions, i.e., ferrofluids, for the first time. A broad knowledge related to the processes responsible for the control of the particle size during the hydrothermal synthesis has been developed. Research of the mechanisms that enable the decrease of the hexaferrite formation temperature prove to be of crucial importance. The developed knowledge enabled us to be the first in the world to synthesize hexaferrite using simple co-precipitation. Secondary re-crystallization also has an important influence on the particle growth during synthesis. In this project the method was developed, which enables complete blocking of the secondary re-crystallization. The method based on the adsorption of oleic acid onto the synthesized nanoparticles is general and can also be applied in the hydrothermal synthesis of other materials.
The synthesis of the ultrafine hexaferrite nanoparticles enabled a study of the adaptation of the material’s crystal structure and the magnetic properties to their very small size (size effect). Both effects are of fundamental importance for the development of nanoscience. As the nanoparticles’ size decrease to reach the dimensions of a few cell parameters of their crystal structure, their structure changes significantly, which also influences the properties. This effect has been intensively studied in the case of ferrites with a simple, cubic-spinel structure. For the basic science, also the research on the influence of the size effect on the complex, layered structure of hexaferrite would be of great interest. The thickness of the disc-like nanoparticles synthesized in the framework of this project barely exceeds one cell parameter of their structure and makes them very interesting for a study of the size effect. In the framework of the project, some of the basic influences of their properties have been explained. However, we believe that the possibility of synthesizing appropriate nanoparticles will trigger further research.
The project contributed to the development of new knowledge regarding the characterization of nanomaterials. In the research on the structural properties of the nanoparticles some sophisticated methods were used, including high-resolution electron microscopy, X-ray diffractometry, and Mossbauer spectroscopy. In the characterisation of the ultrafine nanoparticles, these methods are at the cutting edge. The characterization therefore required the development of new knowledge .
Special attention was given to the development of the knowledge related to the preparation of stable suspensions of the barium hexaferrite nanoparticles in different carrier liquids, i.e., ferrofluids. Ferrofluids have numerous applications in technology and, recently, especially in medicine. In addition, ferrofluids are important as precursors for the syntheses of different magnetic nanocomposite materials. It is expected that our new ferrofluids will be particularly important in the preparation of a number of new nanostructured materials, for example, nanocomposite materials containing nanoparticles dispersed in solid matrixes of a polymer or silica. In this project, the nanocomposite containing a large content of nanoparticles in a methyl methacrylate matrix was prepared. Stable suspensions are also needed for the deposition of nanoparticle layers onto different substrates, for example, with electrophoresis.
In the framework of the project the original method for the preparation of the ferrofluids using the hydrothermal method was developed. The method is based on the synthesis of nanoparticles in the presence of oleic acid as a surfactant. The method is general and appropriate for the preparation of ferrofluids of different materials. For example, the method was already successfully applied in the preparation of ferrofluids based on cobalt-ferrite nanoparticles.
Significance for the country
The synthesis of superparamagnetic, barium-hexaferrite nanoparticles and their stable suspensions, so-called ferrofluids, represents a possible foundation for the development of different new materials, especially nanocomposite materials containing magnetic nanoparticles dispersed in different solid matrixes or deposited onto different substrates. New materials can represent new products with a lot of added value for Slovenian industry. All the procedures developed for the syntheses of nanoparticles and ferrofluids enable a rapid transfer to mass production. One of the possible applications of hexaferrite-containing polymer nanocomposites is in absorbers for the protection of humans and devices against electromagnetic radiation at high frequencies. Thus, the knowledge developed in the framework of this project will not only contribute to the development of new products in Slovenia, but will also be of general importance for the protection against electromagnetic radiation.
Most important scientific results
Annual report
2008,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2008,
final report,
complete report on dLib.si
