Research of the VINCENT Centre is aimed to the structural, magnetic and transport properties of nanosized materials that can be generally described as 3d and/or rare earths oxides which have strong applicative orientation toward technology and biomedicine. The following nanosystems are currently of interest:
- spinel structure oxides:
- ferrites (pure and mixed) of the general formula MFe2O4 (M = Zn, Co, Mn, Ni);
- manganates LiMn2-xMxO4 (M =Zn, Cr, Ti );
- manganites of the general formula R1-xMxMnO3(R=rare earth, M=Ca,Ba,Sr);
- pure and mixed rare earth oxides (R’,R”)O3 (R=rare earth);
- magnetic nanocomposites – magnetic nanoparticles embedded in the diamagnetic nonmetallic matrix (for inst. alpha -, gamma -, epsilon -Fe2O3 /SiO2), or in a polymer host (for inst. (Ni,Fe)-PVA).
Research is aimed towards the influence of the different methods/routes of synthesis on the composition, nanostructural, microstructural and crystallochemical properties of the obtained materials, as well as towards the correlation among these properties and magnetic behavior. For the sake of comparative analysis the polycrystalline counterparts of the above listed materials will be also synthesized.
The research description can be divided into several interconnected parts:
- Synthesis, structure, microstructure and crystallochemistry – To synthesize the above quoted materials several methods will be used: sol-gel, glycine-nitrate, micromicelles, and mechanochemistry. Some samples will be synthesized by several different methods in order to obtain different particle size, distribution and morphology, as well as different structural and microstructural parameters. Characterization of these parameters will be done by TEM/SEM microscopy, and by x-ray and neutron diffraction. Special attention is devoted to the analysis of broadening of the diffraction intensities in order to determine microstructural parameters (crystallite dimension, microstrain and anisotropy) that are important for the analysis of magnetic properties.
Another important aspect is investigation of the influence of the synthesis methods and parameters on the crystallochemical properties of the samples: cationic distribution, stoichiometry, and change of chemical composition with partial cationic replacement. Precise determination of these parameters is of key importance for the analysis of their correlations with magnetic properties.
- Magnetic properties of the nanoparticle magnetic materials – Performing systematic measurements of many magnetic properties and analyze their correlations with structural, microstructural and crystallochemical characteristics. These data are used for determination and improvement of the static and dynamic magnetic properties and synthesis optimization. The final goal is to design the application oriented system that possesses the optimised magnetic and transport properties.
Magnetic properties of nanosystems are also governed by the inter/intra particle interactions of the dipol-dipol and/or exchange type. These interactions are subject of interest both nanopowder samples and in nanocomposites.
Importance of the project:
- Scientific – To establish synthesis methods/routes that produce well defined nanosystems; to understand and systematize correlations among microstructural, crystallochemical and magnetic properties;
- Applicative – To design magnetic nanosystems with optimal characteristics for prospective technological and biomedical applications.