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The present study reports the successful synthesis of Sn 1−x Cr x O 2 nanoparticles with doping content (x) ranging from 0 to 0.20. Samples were synthesized by a polymer precursor method using SnCl 2 •H 2 O and Cr(NO 3 ) 3 •5H 2 O as metal ion suppliers. In all samples X-ray diffraction data show one single-phase formation (rutile-type), with crystalline size (crystal strain) decreasing (increasing) monotonically while increasing the x content, which are assigned to substitutional solution of Cr and Sn ions in the crystalline structure. In addition to a weak magnetic ordering observed in a few samples (x = 0.01, 0.02, 0.03, and 0.05), paramagnetism is the main magnetic contribution in all synthesized samples, which is due to the presence of two chromium ions (Cr 3+ and Cr 4+ ). X-ray photoelectron spectroscopy measurements confirm the coexistence of Cr 3+ and Cr 4+ ions in excellent agreement with the monotonic decrease of the [Cr 3+ ]/[Cr 4+ ] versus doping content (x), assessed from the fitting of the susceptibility versus temperature data using the Curie−Weiss law.

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In this work, we present a coupled experimental and theoretical first-principles investigation on one of the more promising oxide-diluted magnetic semiconductors, the Sn1−xCoxO2 nanoparticle system, in order to see the effect of cobalt doping on the physical and chemical properties.

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In this work, we report on a single-pot synthesis route based on a polymeric precursor method used for successfully producing undoped and iron-doped CeO2 nanoparticles with iron contents up to 10.0 mol. %. The formation of high-crystalline nanoparticles with a cubic fluorite structure is determined for all the studied samples. Meanwhile, the magnetic measurements of the undoped ceria nanoparticles revealed the occurrence of ferromagnetism of bound magnetic polarons of a fraction of Ce3+ at room temperature, and only a paramagnetic behavior of Fe3+ ions was determined for Fe-doped ceria nanoparticles. A monotonous reduction of the effective magnetic moment of the Fe3+ ions was determined. It suggests a change from a high-spin to low-spin state of Fe ions as the Fe content is increased. The 3+ valence state of the iron ions has been confirmed by the Fe K-edge X-ray absorption near-edge structure (XANES) and Mössbauer spectroscopy measurements. X-ray photoelectron spectroscopy data analysis evidenced a coexistence of Ce3+ and Ce4+ ions and a decreasing tendency of the relative fraction of Ce3+ ions in the surface region of the particles as the iron content is increased. Although the coexistence of Ce3+ and Ce4+ is confirmed by results obtained via Ce L3-edge XANES measurements, any clear dependence of the relative relation of Ce3+ ions on the iron content is determined, suggesting a homogeneous distribution of Ce3+ and Ce4+-ions in the whole volume of the particles. Ce L3-edge extended X-ray absorption fine structure revealed that the Ce-O bond distance shows a monotonous decrease as the Fe content is increased, which is in good agreement with the shrinking of the unit cell volume with the iron content determined from XRD data analysis, reinforcing the substitutional solution of Ce and Fe ions in the CeO2 matrix.

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