Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles
In the present study, monodispersed CeO2 nanoparticles (NPs) of size 8.5 ± 1.0, 11.4 ± 1.0 and 15.4 ± 1.0 nm were synthesized using the sol-gel method. Size-dependent structural, optical and magnetic properties of as-prepared samples were investigated by X-ray diffraction (XRD), field emission scann...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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AIP Publishing LLC
2015-02-01
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| Series: | AIP Advances |
| Online Access: | http://dx.doi.org/10.1063/1.4908003 |
| _version_ | 1818791284293238784 |
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| author | Sumeet Kumar Manish Srivastava Jay Singh Samar Layek Madhu Yashpal Arnulf Materny Animesh K. Ojha |
| author_facet | Sumeet Kumar Manish Srivastava Jay Singh Samar Layek Madhu Yashpal Arnulf Materny Animesh K. Ojha |
| author_sort | Sumeet Kumar |
| collection | DOAJ |
| description | In the present study, monodispersed CeO2 nanoparticles (NPs) of size 8.5 ± 1.0, 11.4 ± 1.0 and 15.4 ± 1.0 nm were synthesized using the sol-gel method. Size-dependent structural, optical and magnetic properties of as-prepared samples were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscopy (HR-TEM), ultra-violet visible (UV-VIS) spectroscopy, Raman spectroscopy and vibrating sample magnetometer (VSM) measurements. The value of optical band gap is calculated for each particle size. The decrease in the value of optical band gap with increase of particle size may be attributed to the quantum confinement, which causes to produce localized states created by the oxygen vacancies due to the conversion of Ce4+ into Ce3+ at higher calcination temperature. The Raman spectra showed a peak at ∼461 cm-1 for the particle size 8.5 nm, which is attributed to the 1LO phonon mode. The shift in the Raman peak could be due to lattice strain developed due to variation in particle size. Weak ferromagnetism at room temperature is observed for each particle size. The values of saturation magnetization (Ms), coercivity (Hc) and retentivity (Mr) are increased with increase of particle size. The increase of Ms and Mr for larger particle size may be explained by increase of density of oxygen vacancies at higher calcination temperature. The latter causes high concentrations of Ce3+ ions activate more coupling between the individual magnetic moments of the Ce ions, leading to an increase of Ms value with the particle size. Moreover, the oxygen vacancies may also produce magnetic moment by polarizing spins of f electrons of cerium (Ce) ions located around oxygen vacancies, which causes ferromagnetism in pure CeO2 samples. |
| first_indexed | 2024-12-18T15:08:54Z |
| format | Article |
| id | doaj.art-6631e6e2224c4c058ffdf3988bd6da60 |
| institution | Directory Open Access Journal |
| issn | 2158-3226 |
| language | English |
| last_indexed | 2024-12-18T15:08:54Z |
| publishDate | 2015-02-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | AIP Advances |
| spelling | doaj.art-6631e6e2224c4c058ffdf3988bd6da602022-12-21T21:03:42ZengAIP Publishing LLCAIP Advances2158-32262015-02-0152027109027109-1410.1063/1.4908003009502ADVControlled synthesis and magnetic properties of monodispersed ceria nanoparticlesSumeet Kumar0Manish Srivastava1Jay Singh2Samar Layek3Madhu Yashpal4Arnulf Materny5Animesh K. Ojha6Department of Physics, Motilal Nehru National Institute of Technology, Allahabad-211004, IndiaDepartment of Physics and Astrophysics, University of Delhi, Delhi-110007, IndiaDepartment of Applied Chemistry & Polymer Technology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042, IndiaDepartment of Physics, Indian Institute of Technology, Kanpur 208016, IndiaElectron Microscope Facility, Department of Anatomy Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, IndiaCenter for Functional Materials and Nanomolecular Science, Jacobs University Bremen, Campus Ring, 28759 Bremen, GermanyDepartment of Physics, Motilal Nehru National Institute of Technology, Allahabad-211004, IndiaIn the present study, monodispersed CeO2 nanoparticles (NPs) of size 8.5 ± 1.0, 11.4 ± 1.0 and 15.4 ± 1.0 nm were synthesized using the sol-gel method. Size-dependent structural, optical and magnetic properties of as-prepared samples were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscopy (HR-TEM), ultra-violet visible (UV-VIS) spectroscopy, Raman spectroscopy and vibrating sample magnetometer (VSM) measurements. The value of optical band gap is calculated for each particle size. The decrease in the value of optical band gap with increase of particle size may be attributed to the quantum confinement, which causes to produce localized states created by the oxygen vacancies due to the conversion of Ce4+ into Ce3+ at higher calcination temperature. The Raman spectra showed a peak at ∼461 cm-1 for the particle size 8.5 nm, which is attributed to the 1LO phonon mode. The shift in the Raman peak could be due to lattice strain developed due to variation in particle size. Weak ferromagnetism at room temperature is observed for each particle size. The values of saturation magnetization (Ms), coercivity (Hc) and retentivity (Mr) are increased with increase of particle size. The increase of Ms and Mr for larger particle size may be explained by increase of density of oxygen vacancies at higher calcination temperature. The latter causes high concentrations of Ce3+ ions activate more coupling between the individual magnetic moments of the Ce ions, leading to an increase of Ms value with the particle size. Moreover, the oxygen vacancies may also produce magnetic moment by polarizing spins of f electrons of cerium (Ce) ions located around oxygen vacancies, which causes ferromagnetism in pure CeO2 samples.http://dx.doi.org/10.1063/1.4908003 |
| spellingShingle | Sumeet Kumar Manish Srivastava Jay Singh Samar Layek Madhu Yashpal Arnulf Materny Animesh K. Ojha Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles AIP Advances |
| title | Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles |
| title_full | Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles |
| title_fullStr | Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles |
| title_full_unstemmed | Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles |
| title_short | Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles |
| title_sort | controlled synthesis and magnetic properties of monodispersed ceria nanoparticles |
| url | http://dx.doi.org/10.1063/1.4908003 |
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