Local symmetry and Z-scan analysis of ZnSe/Eu3+ doped sol–gel silica hosts

2010 ◽  
Vol 88 (7) ◽  
pp. 493-500 ◽  
Author(s):  
Siby Mathew ◽  
K. V. Arun Kumar ◽  
C. Sudarsanakumar ◽  
V. P.N. Nampoori ◽  
N. V. Unnikrishnan
Keyword(s):  
Rare Earth ◽  
Sol Gel ◽  
Glass Network ◽  
Local Symmetry ◽  
Wide Distribution ◽  
Rare Earth Ions ◽  
Saturable Absorption ◽  
Rare Earth Ion ◽  
Enhanced Absorption ◽  
The Rare Earth

Vibrational state side-band spectral analysis of silica matrices, doped with ZnSe/Eu3+ ions, associated with the excitation transition 7F0→5D2 is used to analyze the local asymmetry of the rare earth ions in the glass host. The large inhomogeneous linewidth for the ZnSe co-doped samples indicates the wide distribution of the Eu3+ ions in the matrix and is related to the flexibility of the local glass network. The fluorescence spectra reveal that the intensity of the characteristic emission of europium increases considerably in the presence of ZnSe particles. This phenomenon can be explained by the energy transfer resulting from electron–hole recombination in the ZnSe to the rare earth ion. Nonlinear optical absorption of the sample is also investigated at a wavelength of 532 nm, using open aperture Z-scan technique. The sample exhibits reversible saturable absorption (RSA), which is found to depend on excitation fluence. RSA is due to the enhanced absorption resulting from the electron dynamics in nano-crystallites.

Modified TiO2Structures with Enhanced Photoluminescence and Photocatalytic Activity

2021 ◽  
Vol 13 (2) ◽  
pp. 331-341
Author(s):  
Jinqi Wang ◽  
Guopeng Li ◽  
Wei Wang ◽  
Fuxia Li ◽  
Chuankai Yang ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Rare Earth ◽  
Photocatalytic Degradation ◽  
Environmental Remediation ◽  
Rare Earth Ions ◽  
Shell Structures ◽  
Rare Earth Complex ◽  
Core Shell ◽  
Rare Earth Ion ◽  
The Rare Earth

Photocatalytic degradation of pollutants has attracted much attention because it can effectively solve the problem of environmental pollution. SiO2@Eu(TTA)3phen@TiO2 core-shell structures were successfully synthesized for the first time by a solvothermal method involving ultrasound assistance which can optimize the rare earth complex dispersibility and achieve strong emission intensity. SiO2@Eu3+@TiO2 core-shell structures were also successfully synthesized by a similar method. Photocatalytic activity analysis showed that the photocatalytic activity factor not only depended on the rare earth ion content, but also related to the structure and size of the TiO2 nanoparticles. Photocatalytic activity increased first and then decreased with the quantity of rare earth ions. Photocatalytic activity was also superior for hollow structures compared to solid structure. Photocatalytic activity of SiO2@TiO2 particles increased with the particle size, until the size increased to 450 nm. Rare earth ions content as well as particle structures and sizes affected efficiency for the photocatalytic degradation of methyl orange. Outstanding photocatalytic activity provides the composite particles with improved potential to purify aquatic contaminants and to meet the demands of future environmental remediation applications.

scholarly journals Simple Preparation of LaPO4:Ce, Tb Phosphors by an Ionic-Liquid-Driven Supported Liquid Membrane System

2019 ◽  
Vol 20 (14) ◽  
pp. 3424
Author(s):  
Jianguo Li ◽  
Hongying Dong ◽  
Fan Yang ◽  
Liangcheng Sun ◽  
Zhigang Zhao ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Rare Earth ◽  
High Efficiency ◽  
Liquid Membrane ◽  
Membrane System ◽  
Rare Earth Ions ◽  
Raw Material ◽  
Supported Liquid Membrane ◽  
Rare Earth Ion ◽  
The Rare Earth

In this work, LaPO4:Ce, Tb phosphors were prepared by firing a LaPO4:Ce, Tb precipitate using an ionic-liquid-driven supported liquid membrane system. The entire system consisted of three parts: a mixed rare earth ion supply phase, a phosphate supply phase, and an ionic-liquid-driven supporting liquid membrane phase. This method showed the advantages of a high flux, high efficiency, and more controllable reaction process. The release rate of PO43− from the liquid film under different types of ionic liquid, the ratio of the rare earth ions in the precursor mixture, and the structure, morphology, and photoluminescence properties of LaPO4:Ce, Tb were investigated by inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction, Raman spectra, scanning electron microscopy, and photoluminescence emission spectra methods. The results showed that a pure phase of lanthanum orthophosphate with a monoclinic structure can be formed. Due to differences in the anions in the rare earth supply phase, the prepared phosphors showed micro-spherical (when using rare earth sulfate as the raw material) and nanoscale stone-shape (when using rare earth nitrate as the raw material) morphologies. Moreover, the phosphors prepared by this method had good luminescent properties, reaching a maximum emission intensity under 277 nm excitation with a predominant green emission at 543 nm which corresponded to the 5D4-7F5 transition of Tb3+.

Rare-Earth Doped Silicon-Rich Silica: Evidence for Energy Transfer between Silicon Microclusters and Rare-Earth Ions

1994 ◽  
Vol 358 ◽  
Author(s):  
A.J. Kenyon ◽  
P.F. Trwoga ◽  
M. Federighi ◽  
C.W. Pitt
Keyword(s):  
Rare Earth ◽  
Visible Region ◽  
Rare Earth Ions ◽  
Excitation Wavelength ◽  
Rare Earth Ion ◽  
Absorption Bands ◽  
Strong Luminescence ◽  
Doped Silicon ◽  
Rare Earth Doped ◽  
The Rare Earth

ABSTRACTWe report the fabrication of rare-earth doped silicon-rich silica thin films by PECVD. The films exhibit absorption edges in the visible region of the optical spectrum consistent with the presence of silicon microclusters. Weak visible photoluminescence due to silicon microclusters is observed. In addition, strong luminescence from the rare-earth ion is obtained even when excited away from characteristic absorption bands; indeed, the luminescence intensity is largely independent of excitation wavelength below 514 nm. We ascribe this to excitation of silicon microclusters followed by an efficient transfer of energy to the rare-earth ions.The very broad absorption of this material opens up the possibility for flashlamp-pumped optoelectronic devices. In addition, we report the fabrication of silicon-rich silica films by PECVD. We show that the optical properties of these films are consistent with the presence of silicon microclusters and show absorption spectra similar to those of the rare-earth doped silicon-rich silica samples. This supports the hypothesis that the principal absorbing species in the rare-earth doped films is microclustered silicon

THE SOL–GEL SYNTHESIS OF RARE-EARTH IONS SUBSTITUTED BARIUM HEXAFERRITES AND MAGNETIC PROPERTIES

2013 ◽  
Vol 27 (26) ◽  
pp. 1350192 ◽  
Author(s):  
S. CAI ◽  
P. H. XIN ◽  
P. F. WANG ◽  
B. B. ZHANG ◽  
Y. B. HAN ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Magnetic Moments ◽  
Sol Gel ◽  
Barium Hexaferrite ◽  
Anisotropy Field ◽  
Average Diameter ◽  
Rare Earth Ions ◽  
Barium Hexaferrites ◽  
The Rare Earth

In this paper, a series of rare-earth-doped barium hexaferrite powders ( Ba 0.95 Re 0.05- Fe 12 O 19 and Ba 0.95 Re 0.05 M 0.05 Fe 11.95 O 19: Re = La , Pr , Sm , Nd , Gd , Dy , Yb ; M = Zn 2+, Mn 2+, [Formula: see text]) were synthesized by the sol–gel self-combustion technology. The phase composition and the magnetic properties of the as-prepared barium hexaferrites were characterized and discussed with X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The results showed that the barium hexaferrites exhibited the magnetoplumbite phase structure with the average diameter of 45 nm. Magnetic properties study revealed that the variation of the saturation magnetization (Ms) was similar with the change of the rare-earth ions radius, but the change of Ms was low. This indicated that the magnetic moments of rare-earth ions could not affect Ms. The magnetocrystalline anisotropy field mainly influenced the anisotropism of hexaferrites, and the coercivity (Hc) of the rare-earth ions doped barium hexaferrites basically decreased with the increasing orbital quantum numbers (except Sm 3+ and Gd 3+). Further study showed the co-addition of Zn 2+ and Mn 2+ did not change the trend of Ms and Hc. Thus, it is concluded that the rare-earth ions played an important role for the anisotropy field of barium hexaferrites.

Infrared and Electronic Spectra of Rare Earth Perovskites: Ortho-Chromites, -Manganites and -Ferrites

1970 ◽  
Vol 24 (4) ◽  
pp. 436-445 ◽  
Author(s):  
G. V. Subba Rao ◽  
C. N. R. Rao ◽  
J. R. Ferraro
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Transition Metal ◽  
Ir Spectra ◽  
Electronic Spectra ◽  
Transition Metal Ions ◽  
Rare Earth Ions ◽  
Electronic Transitions ◽  
Rare Earth Ion ◽  
The Rare Earth

The electronic and ir spectra of rare earth perovskites of the general formula LnZO3, where Ln is the rare earth ion or yttrium and Z is Cr, Mn, or Fe, have been studied in detail. The results have been discussed in terms of crystallography, magnetic properties, covalency of Ln—O and Z—O bonds, and Goodenough's one electron energy diagrams. In all these compounds the rare earth ions do not markedly affect the electronic transitions of the transition metal ions; the 3 d electrons clearly exhibit localized behavior. Both the electronic and ir spectra of the LnZO3 perovskites are comparable to the spectra of the corresponding transition metal sesquioxides, Z2O3.

scholarly journals Ag-Sensitized Yb3+ Emission in Glass-Ceramics

Micromachines ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 380 ◽  
Author(s):  
Francesco Enrichi ◽  
Elti Cattaruzza ◽  
Maurizio Ferrari ◽  
Francesco Gonella ◽  
Riccardo Ottini ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Rare Earth ◽  
Near Infrared ◽  
Uv Light ◽  
Sol Gel ◽  
Rare Earth Ions ◽  
Information Storage ◽  
Efficient Energy Transfer ◽  
Doped Materials ◽  
The Rare Earth

Rare earth doped materials play a very important role in the development of many photonic devices, such as optical amplifiers and lasers, frequency converters, solar concentrators, up to quantum information storage devices. Among the rare earth ions, ytterbium is certainly one of the most frequently investigated and employed. The absorption and emission properties of Yb3+ ions are related to transitions between the two energy levels 2F7/2 (ground state) and 2F5/2 (excited state), involving photon energies around 1.26 eV (980 nm). Therefore, Yb3+ cannot directly absorb UV or visible light, and it is often used in combination with other rare earth ions like Pr3+, Tm3+, and Tb3+, which act as energy transfer centres. Nevertheless, even in those co-doped materials, the absorption bandwidth can be limited, and the cross section is small. In this paper, we report a broadband and efficient energy transfer process between Ag dimers/multimers and Yb3+ ions, which results in a strong PL emission around 980 nm under UV light excitation. Silica-zirconia (70% SiO2-30% ZrO2) glass-ceramic films doped by 4 mol.% Yb3+ ions and an additional 5 mol.% of Na2O were prepared by sol-gel synthesis followed by a thermal annealing at 1000 °C. Ag introduction was then obtained by ion-exchange in a molten salt bath and the samples were subsequently annealed in air at 430 °C to induce the migration and aggregation of the metal. The structural, compositional, and optical properties were investigated, providing evidence for efficient broadband sensitization of the rare earth ions by energy transfer from Ag dimers/multimers, which could have important applications in different fields, such as PV solar cells and light-emitting near-infrared (NIR) devices.

Fluorescence Line Narrowing Studies of Eu3+-Doped Silica Gel-Glasses

1994 ◽  
Vol 346 ◽  
Author(s):  
M. J. Lochhead ◽  
K. L. Bray
Keyword(s):  
Rare Earth ◽  
Sol Gel ◽  
Rare Earth Ions ◽  
Limiting Factor ◽  
Site Symmetry ◽  
Rare Earth Ion ◽  
Time Resolved ◽  
Line Narrowing ◽  
Fluorescence Line ◽  
Fluorescence Line Narrowing

ABSTRACTBroadband fluorescence and fluorescence line narrowing (FLN) spectra are presented for Eu3+ ions in Eu2O3-SiO3 and Eu2O3-Al2O3-SiO3 systems prepared by the sol-gel process. Clustering of rare earth ions in silica glass can be a limiting factor in the design and engineering of optical device materials. The addition of Al2O3 is known to help disperse rare earth ions in sol-gel silica. In order to develop a more detailed understanding of how Eu3+ is incorporated in these materials, time-resolved, laser-induced FLN studies at 77 K have been performed using a pulsed dye laser to selectively excite subsets of ions in the inhomogeneously broadened 7F0⇆ 5D0 manifold. Fluorescence spectra are discussed in terms of rare earth ion clustering, energy transfer, and bonding site symmetry. It is concluded that Eu3+ ions cluster in sol-gel silica and that the addition of alumina assists in dispersing Eu3+ ions.

Structural, Morphological and Magnetic Characterization of Sm-substituted Ni-Zn Ferrite

2020 ◽  
Vol 10 (2) ◽  
pp. 152-156 ◽  
Author(s):  
Muhammad Hanif bin Zahari ◽  
Beh Hoe Guan ◽  
Lee Kean Chuan ◽  
Afiq Azri bin Zainudin
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Saturation Magnetization ◽  
Sol Gel ◽  
Magnetic Behavior ◽  
Rare Earth Ions ◽  
Ion Concentration ◽  
Zn Ferrite ◽  
Auto Combustion ◽  
Combustion Technique

Background: Rare earth materials are known for its salient electrical insulation properties with high values of electrical resistivity. It is expected that the substitution of rare earth ions into spinel ferrites could significantly alter its magnetic properties. In this work, the effect of the addition of Samarium ions on the structural, morphological and magnetic properties of Ni0.5Zn0.5SmxFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) synthesized using sol-gel auto combustion technique was investigated. Methods: A series of Samarium-substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5SmxFe2-xO4 where x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by sol-gel auto-combustion technique. Structural, morphological and magnetic properties of the samples were examined through X-Ray Diffraction (XRD), Field-Emission Scanning Electron Microscope (FESEM) and Vibrating Sample Magnetometer (VSM) measurements. Results: XRD patterns revealed single-phased samples with spinel cubic structure up to x= 0.04. The average crystallite size of the samples varied in the range of 41.8 – 85.6 nm. The prepared samples exhibited agglomerated particles with larger grain size observed in Sm-substituted Ni-Zn ferrite as compared to the unsubstituted sample. The prepared samples exhibited typical soft magnetic behavior as evidenced by the small coercivity field. The magnetic saturation, Ms values decreased as the Sm3+ concentration increases. Conclusion: The substituted Ni-Zn ferrites form agglomerated particles inching towards more uniform microstructure with each increase in Sm3+ substitution. The saturation magnetization of substituted samples decreases with the increase of samarium ion concentration. The decrease in saturation magnetization can be explained based on weak super exchange interaction between A and B sites. The difference in magnetic properties between the samples despite the slight difference in Sm3+ concentrations suggests that the properties of the NiZnFe2O4 can be ‘tuned’, depending on the present need, through the substitution of Fe3+ with rare earth ions.

scholarly journals Structure, Luminescence, and Magnetic Properties of Crystalline Manganese Tungstate Doped with Rare Earth Ion

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3717
Author(s):  
Jae-Young Jung ◽  
Soung-Soo Yi ◽  
Dong-Hyun Hwang ◽  
Chang-Sik Son
Keyword(s):  
Magnetic Field ◽  
Rare Earth ◽  
Sintering Temperature ◽  
Luminescent Properties ◽  
Concentration Quenching ◽  
Rare Earth Ions ◽  
Precipitation Method ◽  
Rare Earth Ion ◽  
Co Precipitation ◽  
Quenching Phenomenon

The precursor prepared by co-precipitation method was sintered at various temperatures to synthesize crystalline manganese tungstate (MnWO4). Sintered MnWO4 showed the best crystallinity at a sintering temperature of 800 °C. Rare earth ion (Dysprosium; Dy3+) was added when preparing the precursor to enhance the magnetic and luminescent properties of crystalline MnWO4 based on these sintering temperature conditions. As the amount of rare earth ions was changed, the magnetic and luminescent characteristics were enhanced; however, after 0.1 mol.%, the luminescent characteristics decreased due to the concentration quenching phenomenon. In addition, a composite was prepared by mixing MnWO4 powder, with enhanced magnetism and luminescence properties due to the addition of dysprosium, with epoxy. To one of the two prepared composites a magnetic field was applied to induce alignment of the MnWO4 particles. Aligned particles showed stronger luminescence than the composite sample prepared with unsorted particles. As a result of this, it was suggested that it can be used as phosphor and a photosensitizer by utilizing the magnetic and luminescent properties of the synthesized MnWO4 powder with the addition of rare earth ions.

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