Structure-dependent electronic properties of nanocrystalline cerium oxide films

Patsalas, P.; Logothetidis, S.; Sygellou, L.; Kennou, S.

doi:10.1103/physrevb.68.035104

Cited by 335 publications

(208 citation statements)

References 47 publications

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“…Thus, the optical properties of CeO 2 NPs are determined by charge transfer transitions that can be identified by broad bands in the absorption spectra. 26 Patsalas et al 35 have reported that the band gap of the CeO 2 NPs changes with change of Ce 3+ concentration. As the particle size increases, the concentration of Ce 3+ also increases, which causes a decrease of the bandgap for CeO 2 NPs.…”

Section: Uv-vis Spectramentioning

confidence: 97%

Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

et al. 2015

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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.

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Section: Uv-vis Spectramentioning

confidence: 97%

Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

et al. 2015

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“…/Ce 4? ratio increases with the decrease of particle size of the nanocrystal (Wu et al 2004;Patsalas and Logothetidis 2003;Ansari et al 2014). Introduction of Ce 3?…”

Section: Uv-visible Absorptionmentioning

confidence: 99%

Structural studies and luminescence properties of CeO2:Eu3+ nanophosphors synthesized by oxalate precursor method

et al. 2014

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A novel synthesis strategy to prepare CeO 2 :Eu 3? nanophosphors and its luminescence behavior is reported. Different structural characterization techniques such as X-ray diffraction, transmission electron microscope and thermogravimetric analysis reveal that thermal decomposition of oxalate precursor is an effective pathway to produce rare earth oxide nanocrystals. Optical characterizations of the CeO 2 :Eu 3? were done by UV-Visible absorption, photoluminescence excitation and emission spectra. The presence of structural defects and their role on the band gap and luminescence were discussed on the basis of absorption and emission studies.

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“…The fluorescence emission appears at a wavelength close to 500 nm under 430-nm excitation, which is one of the embedded ceria NPs' optical characteristics, with corresponding electron transitions of 5d-4f molecular levels inside the cerium trivalent ionization states, with no fluorescence emission from the pure SS NPs. 27 Comparing to crosslinked PVA nanofibers as cited in Ref. 28, it is observed that the obtained bandgap of ceria becomes lower in case of SS compared to crosslinked PVA host.…”

Section: Optical Propertiesmentioning

confidence: 84%

Optical fluorescent spider silk electrospun nanofibers with embedded cerium oxide nanoparticles

et al. 2018

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"Optical fluorescent spider silk electrospun nanofibers with embedded cerium oxide nanoparticles," J. Nanophoton. 12(2), 026016 (2018), doi: 10.1117/1.JNP.12.026016. Abstract. The work demonstrates an electrospun nanocomposite of recombinant spider silk protein (rSSp) nanofibers with embedded cerium oxide (ceria) nanoparticles. RSSP (MaSp1) has been produced, extracted from goat milk, and fabricated into nanofibers using an electrospinning process. The resulting electrospun nanofibers have a mean diameter of ∼50 nm. Furthermore, ceria nanoparticles of mean diameter <10 nm were added in the spinning dope to be embedded within the generated nanofibers. These nanoparticles show certain optical activity due to optical trivaliant cerium ions, associated with formed oxygen vacancies. The formed nanocomposite shows promising mechanical properties such as the Young's modulus, elasticity (or elongation at break), and toughness. In addition, the electrospun mat becomes fluorescent with 520-nm emission upon exposure to UV light, due to excitation of the optically active ceria nanoparticles. Also, the formed nanocomposite shows a decay of its electric resistance over time upon exposure to cyclic loads at different humidity conditions. The synthesized nanocomposite can be utilized in different biomedical, textile, and sensing applications.

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Structure-dependent electronic properties of nanocrystalline cerium oxide films

Cited by 335 publications

References 47 publications

Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

Structural studies and luminescence properties of CeO2:Eu3+ nanophosphors synthesized by oxalate precursor method

Optical fluorescent spider silk electrospun nanofibers with embedded cerium oxide nanoparticles

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