Denisa Kubániová

Charles University in Prague | CUNI · Department of Low Temperature Physics

The ⁵⁷Fe-enriched polycrystalline perovskite samples Pb1-xBax(Fe0.5Nb0.5)O3, x = 0.25, 0.5, 0.75 were prepared by a solid-state synthesis and studied in detail by X-ray powder diffraction (XRD), neutron diffraction, measurement of magnetic properties, Mössbauer spectroscopy (MoS), and nuclear magnetic resonance (NMR) in a wide temperature range. Th...

Understanding the complex link among composition, microstructure, and magnetic properties paves the way to the rational design of well-defined magnetic materials. In this context, the evolution of the magnetic and structural properties in a series of oleate-capped manganese-substituted cobalt ferrites (MnxCo1–xFe2O4) with variable Co/Mn molar ratio...

Magnetic behaviour of nanoparticles deviates from their bulk equivalents not only due to finite-size and surface effects but it may be also affected by occurrence of metastable states, such as non-equilibrium cation distribution. The chemical composition along with the specific cation distribution are decisive for magnetic properties of spinel ferr...

A wise selection of tracers is critical for magnetic particle imaging (MPI). Most of the current tracers are based on superparamagnetic iron oxide nanoparticles (SPIONs) with a suitable coating. We prepared maghemite cores (γ-Fe2O3) by coprecipitation of Fe(II) and Fe(III) salts with ammonium hydroxide followed by oxidation with hydrogen peroxide a...

The ⁵⁷Fe enriched almost single-phase perovskites Pb(Fe0.5Nb0.5)O3 (PFN) and Ba(Fe0.5Nb0.5)O3 (BFN), prepared by a ceramic method (solid-state synthesis), were studied by Mössbauer spectroscopy, nuclear magnetic resonance (NMR), conventional and synchrotron X-ray powder diffraction (XRD). The temperature dependences of hyperfine and structural para...

A spin-reorientation transition from a weakly ferromagnetic (WF) to an antiferromagnetic (AF) spin ordering in hematite (α-Fe2O3) during cooling occurs at Morin temperature (TM∼264 K for bulk). The transition is strongly size dependent and TM generally decreases with the decreasing volume of the particles. For particles smaller than approximately ∼...

The effects of annealing temperature (1000–1125 °C) and Fe2O3 mass fraction (0.3–0.5) in the initial mixture on the composition of ferric oxide polymorphs within the Fe2O3/SiO2 nanocomposite prepared by sol-gel method were investigated. The structural and magnetic properties of prepared samples were characterized in detail by combination of X-ray p...

Mn-Zn ferrite nanoparticles of the composition Mn0.61Zn0.42Fe1.97O4 and mean size of crystallites dXRD = 11 nm are synthesized under hydrothermal conditions as a single-phase product. Subsequently, two coated samples are prepared by encapsulation of the ferrite particles into silica and titania. Transmission electron microscopy confirms the core-sh...

Magnetic nanoparticles have found broad applications in medicine, especially for cell targeting and transport, and as contrast agents in MRI. Our samples of e-Fe2O3 nanoparticles were prepared by annealing in silica matrix, which was leached off and the bare particles were then coated with amorphous silica layers of various thicknesses. The distrib...

NANOPERM-type alloy with chemical composition Fe76Mo8CuB15 was studied by combination of 57Fe Mössbauer spectroscopy and 57Fe(10B, 11B) nuclear magnetic resonance in order to determine distribution of hyperfine magnetic fields and evolution of relative concentration of Fe-containing crystalline phases within the surface layer and the volume of the...

Iron-based nanoparticles prepared by precipitation from solid solution of saturated binary Cu-Fe alloy were studied by transmission electron microscopy, high-energy X-ray diffraction and Mössbauer spectroscopy. The results showed that the investigated as-prepared nanoparticles contained two phases. The major phase was determined as α−Fe and the min...

The nanoparticles of ε-Fe2O3 enriched with 57Fe isotope in amorphous silica matrix were prepared by sol-gel technique starting from a single molecular precursor for both Fe2O3 and silica. From the X-ray powder diffraction pattern ε-Fe2O3 was identified as the major phase and α-Fe2O3 and β-Fe2O3 were observed as minor iron oxide phases. Using the lo...

Low temperature (4.2 K) magnetic behavior of Fe76 Mo 8Cu1B15 metallic glass was studied by 57Fe Mössbauer spectrometry (MS) and 57Fe NMR. Distributions of hyperfine magnetic fields P(B) were determined for as-quenched and annealed (nanocrystalline) samples with relative fraction of the grains about 43%. P(B) distributions were derived for both the...