Nanostructure and magnetic anomaly of mechanosynthesized Ce1−x_{1-x}Yx_{x}O2−δ_{2-δ} (x ≤ 0.3) solid solutions

Electromagnetic properties of complex oxide solid solutions containing Ce and Y attract increasing interests due to their high application potential. Their properties are known to be dependent on many factors including grain size and crystal defects. Here we focus on unique features of nanocrystalline Ce$_{1-x}$Y$_{x}$O$_{2-δ}$ (x ≤ 0.3) solid solutions prepared via a mechanosynthesis. Mechanically activated CeO$_{2-δ}$ and mechanosynthesized Ce$_{1-x}$Y$_{x}$O$_{2-δ}$ exhibit room-temperature ferromagnetism. The saturation magnetization reaches maximum for the Ce$_{0.9}$Y$_{0.1}$O$_{2-δ}$ solid solution. XPS and Raman spectra show that Ce$^{Zahl}$4+s are partially reduced to Ce$^{3+}$, with simultaneous introduction of oxygen vacancies accumulated on surface of the solid solutions. An analysis of the experimental magnetization data and the determination of both the spin state and the concentration of magnetic carriers revealed that a small part of the Ce$^{3+}$ spins (<1%) is responsible for the magnetic state of the Ce$_{1-x}$Y$_{x}$O$_{2-δ}$ system. Existence of clusters with a short-range antiferromagnetic order is also suspected

Combined mechanochemical/thermal synthesis of microcrystalline pyroxene LiFeSi2O6 and one-step mechanosynthesis of nanoglassy LiFeSi2O6-based composite

Both, microcrystalline LiFeSi2O6 pyroxene and nanoglassy LiFeSi2O6-based composite are prepared via non-conventional mechanochemical/ thermal processing and one-step mechanosynthesis, respectively. The structural state of the as-prepared materials on the long-range and local atomic scales is characterized by XRD and Fe-57 Mossbauer spectroscopy, respectively. The derived hyperfine interaction parameters indicate that the nanoglassy nature of the mechanosynthesized LiFeSi2O6-based composite is characterized, on the short-range scale, by a broadly distorted geometry of the constituent structural units, and on the long-range scale, by the raptured chains of the edge-sharing FeO6 octahedra and of the corner-sharing SiO4 tetrahedra.Web of Science70731431

Evidence of tetrahedrally coordinated nickel cations in nanostructured NiFe2O4

Nanostructured nickel ferrite (NiFe2O4) is prepared via high-energy ball milling of the bulk counterpart at ambient temperature. The structure of the as-prepared nanoferrite is characterized by Raman spectroscopy and Fe-57 Mossbauer spectroscopy. Due to the ability of these spectroscopic techniques to probe the local environment of ions, valuable complementary insight into the nature of the local structural disorder of nanosized NiFe2O4, is provided. For the first time, evidence is given of the tetrahedrally coordinated nickel cations in the nanomaterial.Web of Science1963657365