Effects of Gd doping on the structural, optical and magnetic properties of Ce1−xGdxO2−δ nanoparticles and the impact of the oxygen vacancy

• Published in: Journal of alloys and compounds Vol. 960
• Main Authors: Conceição, E.J.F., Aragón, F.F.H., Urian, Y.A., Castro, T.J., Coaquira, J.A.H., Morais, P.C., da Silva, S.W.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-10-2023
• Subjects: Gd-doped CeO2; Magnetic nanoparticle; Oxygen vacancy; Phonon confinement model; Room temperature antiferromagnetism; Room temperature ferromagnetism; Magnetic nanoparticle; Phonon confinement model; Room temperature ferromagnetism; Gd-doped CeO2; Room temperature antiferromagnetism; Oxygen vacancy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2023.170628

In this study, we report on the structural, optical and magnetic properties of Ce1−xGdxO2−δ nanoparticles (NPs) (0.00 ≤x≤ 0.20) synthesized by the polymeric precursor method. The synthesis protocol successfully fabricated single-phase NPs in the whole range of x-values investigated. The samples were studied by using x-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV-Vis absorption, Raman spectroscopy, and vibrating sample magnetometry (VSM). TEM images and XRD analyses revealed the formation of fully crystalline single-phase cubic fluorite NPs having a mean crystallite size in the range of 6 – 4 nm. XRD data analysis showed a linear increase of the lattice constant with Gd-content (x), evidencing an effective incorporation of Gd3+-ions substituting Ce4+-ions in the cerium oxide matrix. The quantitative analysis of the Raman spectra revealed a gradual increase of defects concentration as the Gd-content increased. In order to maintain charge neutrality, it was observed that the formation of intrinsic oxygen vacancy follows different behavior depending on the Gd-content. This result is in agreement with the Gd-content dependence of optical band gap determined from UV visible absorption spectra. The analysis of magnetic measurements revealed the coexistence of ferromagnetic and paramagnetic contributions. At room temperature, the ferromagnetic contribution show a maximum saturation magnetization (Ms) for the sample with x = 0.02 and a decreasing trend for higher x values. 5 K magnetic measurements data analysis corroborates with the Raman spectroscopy data analysis. The paramagnetic contribution follows a typical paramagnetic Curie-Weiss behavior with antiferromagnetic/ferromagnetic correlations, which depend on the Ce3+- and Gd3+-contents.
•Ce1−xGdxO2−δ (0.00 ≤x≤ 2.00) nanoparticles were synthesized by a polymeric precursor method.•Gd3 + and Ce3 + ions contents per unit cell as a function Gd-content were determined from Raman spectroscopy and M × H data.•Saturation magnetization in Ce1−xGdxO2−δ NPs depends on both the Gd3 + and Ce3 + contents.