MÖSSBAUER SPECTROSCOPY ON MAGNETITE NANOPARTICLES

B. Kalska-Szostko, K. Kropiewnicka

University of Bialystok, Institute of Chemistry, Hurtowa 1, 15-399 Bialystok, Poland

In last decade a lot of research is focused on nanotechnology. It become very important subject in physics, medicine, biology and chemistry. This is due to the potential applications of a novel materials in many areas of life. The reduced dimension leads to the new chemical and physical properties, which are not known from the bulk or even thin films materials. The new interesting properties are mainly related to the large surface-to-volume ratio and broken symmetry at the surface. In such systems the quantum-size effects, in many cases, must be taken into account for interpretation of the results.

The chemical route for the nanoparticles preparation is the optional one to many proposed by physical means. Wet chemical methods are challenging for the scientists because most of them are quite cheap (compare to others methods) and can produce a lot of final materials in one batch. However, it was observe before, that the conditions of the sample preparation have large influence on their final properties. For example, the nominally the same samples are showing different Mössbauer spectra, what suggests the influence of chemical environment of the particles on their magnetic properties or the structure.

The studies on the relation between the oxide particles formation condition and their properties will be shown. We are focused on the problem of the influence of the pH, solvent, surfactant and Fe²⁺/Fe³⁺ ratio (of the starting constituents) on the quality of the particles. We are trying to find the best conditions how to prepare pure, single phase nanoparticles. Since the distinguishing between Fe₃O₄, g-Fe₂O₃ or a-Fe₂O₃ is quite difficult (especially in the nanosystems) we are looking for the easy way how to test the sample to be sure that the particles are single phase. In the studies the problem of the separation of the different type of the oxides we are faced. Quite significant influence on the particle size from the substitution elements such as Co, Ni, Mn are observed.

The Mössbauer spectroscopy is used as a main tool of characterization of the system since the method is very sensitive to any modification of the composition and the structure of the particles.