The Composition and Magnetic Structure of Fe3O4/γ-Fe2O3 Core-Shell Nanocomposites under External Magnetic Field: Mössbauer Study (Part II)

Influence of functionalization with citric acid on the properties of magnetic nanoparticles Zn-=SUB=-x-=/SUB=-Fe-=SUB=-3-x-=/SUB=-O-=SUB=-4-=/SUB=- (0≤ x≤ 1.0)

“…The magnetic properties and phase state of the synthesized MNPs were investigated using Mössbauer spectroscopy, which has a high sensitivity to nuclear ultrafine interactions and allows unambiguous identification of iron oxides [14,25,26,33,34,[48][49][50], which is not available to other methods. Mössbauer spectra (MS) of the synthesized MNPs were obtained using a spectrometer with registration of gamma-quanta from the source Co 57 (Rh) in the geometry of transmission through the sample.…”

“…The main advantages of Mössbauer spectroscopy are that this method allows you to confidently establish the phase composition, the distribution of ions in non-equivalent positions, the magnetic structure, the percentage of compounds with iron and ultrafine interactions in iron-containing materials [24][25][26]33,34,[48][49][50]. This is due to the possibilities of Mössbauer spectroscopy for the unambiguous identification of iron oxides, which is practically inaccessible to other methods.…”

“…The process of such fitting includes: (1) a set of sextuplets whose relaxation times exceed the limit of the time window of the experiment (10 −8 s), and therefore reveal blocked particles, (2) quadrupole doublets formed from superparamagnetic particles whose relaxation times are less than the value of the time window (10 −8 s), and (3) Zeeman sextuplets with wide lines whose relaxation times are intermediate. Analysis of P(H eff ) curves makes it possible to establish the components of sextuplets (and doublets) and draw conclusions about the belonging of these components to the corresponding iron oxides and positions of Fe ions in the crystal lattice [25,26,33,34,50]. The method of processing experimental Mössbauer spectra using the program [51] allows for their qualitative analysis [25,26,33,34,50].…”

“…Analysis of P(H eff ) curves makes it possible to establish the components of sextuplets (and doublets) and draw conclusions about the belonging of these components to the corresponding iron oxides and positions of Fe ions in the crystal lattice [25,26,33,34,50]. The method of processing experimental Mössbauer spectra using the program [51] allows for their qualitative analysis [25,26,33,34,50].…”

“…In addition, synthesized MNPs can be toxic and not biologically compatible. In connection with these requirements, hybrid MNPs of the core/shell type are created, the protective shell of which is silicon dioxide [24] or biologically compatible iron oxides [25,26]. Secondly, magnetic liquids (ML), developed for introduction into a living organism, are a mixture of MNPs dispersed into an aqueous medium or other liquids.…”