Heavily impregnated ceria nanoparticles with europium oxide: spectroscopic evidences for homogenous solid solutions and intrinsic structure of Eu3+-oxygen environments

Avram, Daniel; Rotaru, C.G.; Cojocaru, Bogdan; Sanchez-Dominiguez, Margarita; Florea, Mihaela; Tiseanu, Carmen

doi:10.1007/s10853-013-7904-6

Cited by 29 publications

(31 citation statements)

References 30 publications

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“…The data confirm definitely the two -centre distribution suggested by our previous room -temperature, twowavelength excited luminescence investigations 20 . The spectrum I is obtained by excitation into ceria O 2--Ce 4+ charge-transfer (CT) band of CeO 2 and assigned to Eu substituting for the cubic Ce 4+ lattice sites (the emission is dominated by the allowed magnetic dipole (MD) transition around 591 nm; the MD and ED forbidden 5 D 0 -7 F 0 emission around 579 nm is absent).…”

Section: Evidence For a Two -Centre Model Of Ln Emission In Ceosupporting

confidence: 91%

Toward a Unified Description of Luminescence–Local Structure Correlation in Ln Doped CeO₂ Nanoparticles: Roles of Ln Ionic Radius, Ln Concentration, and Oxygen Vacancies

et al. 2015

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We propose a physical model for luminescence properties of trivalent lanthanide (Ln) doped into CeO 2 by use of low temperature, site selective, time-gated luminescence spectroscopy seconded by X-ray diffraction, Raman and Fourier transform infrared spectroscopy and transmission electron microscopy. The main findings can be summarized as follows: i) Ln situated to both left and right side to Gd in the Ln series, exhibit a two center distribution. Both Ln centers substitute for the tetravalent Ce fluorite sites being differentiated by the local symmetry: cubic, as a result of zero vacancy in the nearest-neighbor oxygen shell (cubic Ln center) and low symmetry, likely due to one vacancy in the nearest-neighbor oxygen shell (Ln -defect associate center); ii) A first example of Dy emission in an inversion (cubic) symmetry, characterized by strong lines at 679 and 764 nm is reported. This results is expected to challenge the way this lanthanide is currently used as a luminescence probe; iii) the relative contribution of the Ln centers to the overall emission depends on the Ln ionic radius: Sm exists predominantly as a cubic center while Er is found mostly as a vacancy associate; iv) Er, La codoped CeO 2 can be used as an effective model system to separate the effects of Ln concentration and subsequently induced oxygen vacancies on the efficiency of CeO 2 sensitization of Ln emission and v) Zr co -doping of CeO 2 obstructs the formation of Ln -defect associates. The implications of our findings for the interpretation of data already present in the literature are also discussed.

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Section: Evidence For a Two -Centre Model Of Ln Emission In Ceosupporting

confidence: 91%

Toward a Unified Description of Luminescence–Local Structure Correlation in Ln Doped CeO₂ Nanoparticles: Roles of Ln Ionic Radius, Ln Concentration, and Oxygen Vacancies

et al. 2015

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“…Figure 3b presents the Raman spectra of ZnO, Eu-doped ZnO nanoparticles, and Eu 2 O 3 in the wavenumber range 2000-8000 cm -1 . In this range, only the Eu-doped ZnO nanoparticles present bands and these bands are specific to Eu 2 O 3 [46]. It should be noted here that for 0.1 mol% Eu all these bands exhibit low intensities, while for higher concentrations these bands are better resolved.…”

Section: Raman Spectroscopymentioning

confidence: 62%

A valence states approach for luminescence enhancement by low dopant concentration in Eu-doped ZnO nanoparticles

et al. 2015

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The paper presents a simple, reproducible, controllable, and direct wet chemical synthesis method for Zn 1-x Eu x O nanoparticles. The full understanding of decomposition mechanism of the as-obtained oxalate precipitate was achieved based on the thermal analysis correlated with the evolved gas analysis and FTIR spectroscopy. The structure, morphology, and optical luminescent properties of the Zn 1-x Eu x O nanoparticles have been investigated by X-ray diffraction, Raman spectroscopy, HRTEM, SAED, XPS, and PL. The XRD studies reveal the formation of a hexagonal wurtzite-type structure. The presence of Eu 2 O 3 cubic structure can be observed up to 0.5 mol% Eu, suggesting that the solubility of the divalent or trivalent Eu into the ZnO lattice is limited. The formation of Eu 2 O 3 secondary phase at higher Eu concentration is sustained by Raman spectroscopy and XPS, as well. The TEM investigations of the Eu-doped ZnO samples illustrate the presence of aggregates with different shapes and dimensions formed by agglomerated spherical and polyhedral nanoparticles with sizes ranging from 20 to 120 nm. The effect of europium concentration on the structural and morphological characteristics, as well as on the luminescent properties was studied with special emphasis on the europium chemical states-Eu 2? and Eu 3? . The PL measurements sustain the presence of both divalent and trivalent europium ions into the ZnO host lattice and, at the same time, an increase of its defects density induced by the dopant presence.

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“…It should be noted that the ability of a nanosized fluorite oxide of dissolving high amount of lanthanide oxides (up to 30%) by wet impregnation was first suggested by Corma et al [55] for the fluorite-structured oxide of Ce (CeO 2 ) and confirmed in subsequent studies by some of us [56,57]. We note that the tetragonal structure (along with the monoclinic one) originates from the parent fluorite (CaF 2 ) structure [4].…”

Section: Resultsmentioning

confidence: 78%

Full Tetragonal Phase Stabilization in ZrO2 Nanoparticles Using Wet Impregnation: Interplay of Host Structure, Dopant Concentration and Sensitivity of Characterization Technique

et al. 2018

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Here, we show that wet impregnation of ZrO2 nanoparticles with 10% and 20% Eu oxide followed by thermal anneal in air above 500 °C produces full stabilization of the tetragonal phase of ZrO2 without evidencing any phase separation. The bare ZrO2 nanoparticles were obtained using three synthetic methods: oil in water microemulsion, rapid hydrothermal, and citrate complexation methods. The homogeneity of the solid solutions was assessed using X-ray diffraction, Raman spectroscopy, high resolution transmission electron microscopy, and advanced luminescence spectroscopy. Our findings show that wet impregnation, which is a recognized method for obtaining surface doped oxides, can be successfully used for obtaining doped oxides in the bulk with good homogeneity at the atomic scale. The limits of characterization technique in detecting minor phases and the roles of dopant concentration and host structure in formation of phase stabilized solid solutions are also analyzed and discussed.

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Heavily impregnated ceria nanoparticles with europium oxide: spectroscopic evidences for homogenous solid solutions and intrinsic structure of Eu3+-oxygen environments

Cited by 29 publications

References 30 publications

Toward a Unified Description of Luminescence–Local Structure Correlation in Ln Doped CeO₂ Nanoparticles: Roles of Ln Ionic Radius, Ln Concentration, and Oxygen Vacancies

Toward a Unified Description of Luminescence–Local Structure Correlation in Ln Doped CeO₂ Nanoparticles: Roles of Ln Ionic Radius, Ln Concentration, and Oxygen Vacancies

A valence states approach for luminescence enhancement by low dopant concentration in Eu-doped ZnO nanoparticles

Full Tetragonal Phase Stabilization in ZrO2 Nanoparticles Using Wet Impregnation: Interplay of Host Structure, Dopant Concentration and Sensitivity of Characterization Technique

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Heavily impregnated ceria nanoparticles with europium oxide: spectroscopic evidences for homogenous solid solutions and intrinsic structure of Eu3+-oxygen environments

Cited by 29 publications

References 30 publications

Toward a Unified Description of Luminescence–Local Structure Correlation in Ln Doped CeO2 Nanoparticles: Roles of Ln Ionic Radius, Ln Concentration, and Oxygen Vacancies

Toward a Unified Description of Luminescence–Local Structure Correlation in Ln Doped CeO2 Nanoparticles: Roles of Ln Ionic Radius, Ln Concentration, and Oxygen Vacancies

A valence states approach for luminescence enhancement by low dopant concentration in Eu-doped ZnO nanoparticles

Full Tetragonal Phase Stabilization in ZrO2 Nanoparticles Using Wet Impregnation: Interplay of Host Structure, Dopant Concentration and Sensitivity of Characterization Technique

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Toward a Unified Description of Luminescence–Local Structure Correlation in Ln Doped CeO₂ Nanoparticles: Roles of Ln Ionic Radius, Ln Concentration, and Oxygen Vacancies

Toward a Unified Description of Luminescence–Local Structure Correlation in Ln Doped CeO₂ Nanoparticles: Roles of Ln Ionic Radius, Ln Concentration, and Oxygen Vacancies