Magnetism mediated by a majority of [Fe³⁺ + $\mathbf{V}_{\mathbf{O}}^{\mathbf{2-}}$ ] complexes in Fe-doped CeO₂nanoparticles

Abstract

We examine the role of Fe(3+) and vacancies (V(O)) on the magnetism of Fe-doped CeO2 nanoparticles. Magnetic nanoparticles of Ce(100-x)Fe(x)O2 (x = 0, 0.26, 1.82, 2.64, 5.26, 6.91, and 7.22) were prepared by a co-precipitation method, and their structural, compositional and magnetic properties were investigated. The CeO2 nanoparticles had a mixed valance of Ce(4+) and Ce(3+) ions, and doping introduced Fe(3+) ions. The decrease in Ce(3+) and increase in Fe(3+) concentrations indicated the presence of more [Fe(3+) + V(O)(2-)] complexes with Fe loading in the particles. Charge neutralization, Fe(3+) + V(O)(2-) + 2Ce(4+) ↔ 2Ce(3+) + Fe(3+), identified the impact of V(O) on the magnetism, where our results suggest that the Fe-doped CeO2 nanoparticle magnetism is mediated by a majority of [Fe(3+) + V(O)(2-)]-Ce(3+) -[Fe(3+) + V(O)(2-)] complexes.

Enhanced Room‐Temperature Ferromagnetism in Composite CeO2/CeF3 Nanoparticles

“…Doping ceria with aliovalent cations such as rare earth or transition metal ions generates more vacancies and in a number of cases leads to better performance parameters as well as to the enhancement of room temperature ferromagnetism . A considerably lower number of publications are devoted to the studies of anion doping effects to ceria.…”

Synergy between Fe and Promoter Ions Supported on Nanoceria Influences NOx Reduction Catalysis

“…The nanocrystallite sizes were ∼20 nm, and the lattice constants of ∼5.413 Å are identical with the 5.414 Å value of bulk ceria . The XRD patterns also indicate that the Fe ions are decorating the surface of the nanoceria; if Fe 3+ (0.64 Å) ions replaced Ce 4+ (1.01 Å) ions, the lattice constant should decrease . The nature of the Fe ions as supported on CeO 2 is further evidenced by the TEM and HAADF images (Figure ).…”

“…8 The XRD patterns also indicate that the Fe ions are decorating the surface of the nanoceria; if Fe 3+ (0.64 Å) ions replaced Ce 4+ (1.01 Å) ions, the lattice constant should decrease. 26 The nature of the Fe ions as supported on CeO 2 is further evidenced by the TEM and HAADF images (Figure 1). Note that the relatively large size distribution of crystallites in the TEM images is not related to the decoration synthesis discussed above but is intrinsic to the obtained nanoceria support (e.g., an X-ray diffraction pattern along with its Rietveld refinement and a TEM image of a nanoceria support are provided in Figure S2).…”

Insights into the Fe3+ Doping Effects on the Structure and Electron Distribution of Cr2O3 Nanoparticles

“…Despite these exciting results, no one, to the best of our knowledge, has hitherto reported experimental or both theoretical and experimental studies focused on the crystal structure and conductivity performance of Fe 3+ -doped Cr 2 O 3 nanoparticles. Actually, when Fe is substitute for Cr, the Fe site is expected to be different from the Cr site in Cr 2 O 3 due to the slightly smaller ionic radius of chromium ( r 3+ Cr = 0.605 Å) [ 54 ] compared to that of Fe ( r 3+ Fe = 0.645 Å) [ 55 ] in octahedral sites. Consequently, an understanding the local environment around the chromium atom is needed to explain the evolution of the physical properties concerning the chromium content x in Cr 2− x Fe x O 3 .…”