The Influence of Light Rare-Earth Substitution on Electronic and Magnetic Properties of CoFe<sub>2</sub>O<sub>4</sub> Nanoparticles
Co<sub>0.95</sub>R<sub>0.05</sub>Fe<sub>2</sub>O<sub>4</sub> nanoparticles with R = La, Pr, Nd, Sm, and Eu were synthesized via an environmentally friendly sol–gel method. The prepared samples were studied using X-ray diffraction measurements (XRD), tr...
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MDPI AG
2025-07-01
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| author | Rareș Bortnic Adam Szatmari Tiberiu Dragoiu Radu George Hategan Roman Atanasov Lucian Barbu-Tudoran Coriolan Tiusan Raluca Lucacel-Ciceo Roxana Dudric Romulus Tetean |
| author_facet | Rareș Bortnic Adam Szatmari Tiberiu Dragoiu Radu George Hategan Roman Atanasov Lucian Barbu-Tudoran Coriolan Tiusan Raluca Lucacel-Ciceo Roxana Dudric Romulus Tetean |
| author_sort | Rareș Bortnic |
| collection | DOAJ |
| description | Co<sub>0.95</sub>R<sub>0.05</sub>Fe<sub>2</sub>O<sub>4</sub> nanoparticles with R = La, Pr, Nd, Sm, and Eu were synthesized via an environmentally friendly sol–gel method. The prepared samples were studied using X-ray diffraction measurements (XRD), transmission electron microscopy (TEM), X-ray photoelectron microscopy (XPS), and magnetic measurements. All compounds were found to be single phases adopting a cubic <i>Fd-3m</i> structure. EDS analysis confirmed the presence of Co, Fe, R, and oxygen in all cases. The XPS measurements reveal that the Co 2<i>p</i> core-level spectra are characteristic for Co<sup>3+</sup> ions, as indicated by the 2<i>p</i><sub>3/2</sub> and 2<i>p</i><sub>1/2</sub> binding energies and spin–orbit splitting values. The analysis of the Fe 2<i>p</i> core-level spectra reveals the presence of both Fe<sup>3+</sup> and Fe<sup>2+</sup> ions in the investigated samples. The doped samples exhibit lower saturation magnetizations than the pristine sample. Very good agreement with the saturation magnetization values was obtained if we assumed that the light rare-earth ions occupy octahedral sites and their magnetic moments align parallel to those of the 3<i>d</i> transition metal ions. The ZFC-FC curves indicate that some nanoparticles remain superparamagnetic, while others exhibit ferrimagnetic ordering at room temperature, suggesting the presence of interparticle interactions. The M<sub>r</sub>/M<sub>s</sub> ratio at room temperature reflects the dominance of magnetostatic interactions. |
| format | Article |
| id | doaj-art-384acd7251bf4f61b5b8a7e7a14a77f0 |
| institution | DOAJ |
| issn | 2079-4991 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
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| series | Nanomaterials |
| spelling | doaj-art-384acd7251bf4f61b5b8a7e7a14a77f02025-08-20T03:04:43ZengMDPI AGNanomaterials2079-49912025-07-011515115210.3390/nano15151152The Influence of Light Rare-Earth Substitution on Electronic and Magnetic Properties of CoFe<sub>2</sub>O<sub>4</sub> NanoparticlesRareș Bortnic0Adam Szatmari1Tiberiu Dragoiu2Radu George Hategan3Roman Atanasov4Lucian Barbu-Tudoran5Coriolan Tiusan6Raluca Lucacel-Ciceo7Roxana Dudric8Romulus Tetean9Faculty of Physics, “Babes Bolyai” University, Kogalniceanu 1, 400084 Cluj-Napoca, RomaniaFaculty of Physics, “Babes Bolyai” University, Kogalniceanu 1, 400084 Cluj-Napoca, RomaniaFaculty of Physics, “Babes Bolyai” University, Kogalniceanu 1, 400084 Cluj-Napoca, RomaniaFaculty of Physics, “Babes Bolyai” University, Kogalniceanu 1, 400084 Cluj-Napoca, RomaniaFaculty of Physics, “Babes Bolyai” University, Kogalniceanu 1, 400084 Cluj-Napoca, RomaniaElectron Microscopy Center “Prof. C. Craciun”, Faculty of Biology & Geology, “Babes-Bolyai” University, 5-7 Clinicilor St., 400006 Cluj-Napoca, RomaniaFaculty of Physics, “Babes Bolyai” University, Kogalniceanu 1, 400084 Cluj-Napoca, RomaniaFaculty of Physics, “Babes Bolyai” University, Kogalniceanu 1, 400084 Cluj-Napoca, RomaniaFaculty of Physics, “Babes Bolyai” University, Kogalniceanu 1, 400084 Cluj-Napoca, RomaniaFaculty of Physics, “Babes Bolyai” University, Kogalniceanu 1, 400084 Cluj-Napoca, RomaniaCo<sub>0.95</sub>R<sub>0.05</sub>Fe<sub>2</sub>O<sub>4</sub> nanoparticles with R = La, Pr, Nd, Sm, and Eu were synthesized via an environmentally friendly sol–gel method. The prepared samples were studied using X-ray diffraction measurements (XRD), transmission electron microscopy (TEM), X-ray photoelectron microscopy (XPS), and magnetic measurements. All compounds were found to be single phases adopting a cubic <i>Fd-3m</i> structure. EDS analysis confirmed the presence of Co, Fe, R, and oxygen in all cases. The XPS measurements reveal that the Co 2<i>p</i> core-level spectra are characteristic for Co<sup>3+</sup> ions, as indicated by the 2<i>p</i><sub>3/2</sub> and 2<i>p</i><sub>1/2</sub> binding energies and spin–orbit splitting values. The analysis of the Fe 2<i>p</i> core-level spectra reveals the presence of both Fe<sup>3+</sup> and Fe<sup>2+</sup> ions in the investigated samples. The doped samples exhibit lower saturation magnetizations than the pristine sample. Very good agreement with the saturation magnetization values was obtained if we assumed that the light rare-earth ions occupy octahedral sites and their magnetic moments align parallel to those of the 3<i>d</i> transition metal ions. The ZFC-FC curves indicate that some nanoparticles remain superparamagnetic, while others exhibit ferrimagnetic ordering at room temperature, suggesting the presence of interparticle interactions. The M<sub>r</sub>/M<sub>s</sub> ratio at room temperature reflects the dominance of magnetostatic interactions.https://www.mdpi.com/2079-4991/15/15/1152rare-earth cobalt ferrite nanoparticleselectronic structuremagnetic properties |
| spellingShingle | Rareș Bortnic Adam Szatmari Tiberiu Dragoiu Radu George Hategan Roman Atanasov Lucian Barbu-Tudoran Coriolan Tiusan Raluca Lucacel-Ciceo Roxana Dudric Romulus Tetean The Influence of Light Rare-Earth Substitution on Electronic and Magnetic Properties of CoFe<sub>2</sub>O<sub>4</sub> Nanoparticles Nanomaterials rare-earth cobalt ferrite nanoparticles electronic structure magnetic properties |
| title | The Influence of Light Rare-Earth Substitution on Electronic and Magnetic Properties of CoFe<sub>2</sub>O<sub>4</sub> Nanoparticles |
| title_full | The Influence of Light Rare-Earth Substitution on Electronic and Magnetic Properties of CoFe<sub>2</sub>O<sub>4</sub> Nanoparticles |
| title_fullStr | The Influence of Light Rare-Earth Substitution on Electronic and Magnetic Properties of CoFe<sub>2</sub>O<sub>4</sub> Nanoparticles |
| title_full_unstemmed | The Influence of Light Rare-Earth Substitution on Electronic and Magnetic Properties of CoFe<sub>2</sub>O<sub>4</sub> Nanoparticles |
| title_short | The Influence of Light Rare-Earth Substitution on Electronic and Magnetic Properties of CoFe<sub>2</sub>O<sub>4</sub> Nanoparticles |
| title_sort | influence of light rare earth substitution on electronic and magnetic properties of cofe sub 2 sub o sub 4 sub nanoparticles |
| topic | rare-earth cobalt ferrite nanoparticles electronic structure magnetic properties |
| url | https://www.mdpi.com/2079-4991/15/15/1152 |
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