scholarly journals Revealing the substitution mechanism in Eu3+:CaMoO4 and Eu3+,Na+:CaMoO4 phosphors

2018 ◽  
Vol 6 (47) ◽  
pp. 12830-12840 ◽  
Author(s):  
Ana Isabel Becerro ◽  
Mathieu Allix ◽  
Mariano Laguna ◽  
Daniel González-Mancebo ◽  
Cecile Genevois ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Unit Cell ◽  
Co Doping ◽  
Substitution Mechanism ◽  
The Eu

Why is the Eu3+:CaMoO4 unit cell bigger than that of CaMoO4? Does Na+ co-doping improve the quantum yield of Eu3+:CaMoO4 phosphors?

Synergistic Effect of Eu3+ and Sm3+ Co-Doping on Photocatalytic Activity of TiO2 Nanoparticles

2011 ◽  
Vol 197-198 ◽  
pp. 891-894 ◽  
Author(s):  
Cheng Zhi Jiang ◽  
Xu Dong Lu
Keyword(s):  
Photocatalytic Activity ◽  
Synergistic Effect ◽  
Sol Gel ◽  
Blue Shift ◽  
Nano Particles ◽  
Absorption Profile ◽  
Co Doping ◽  
The Matrix ◽  
Co Doped ◽  
The Eu

Pure TiO2, Eu3+and Sm3+co-doping TiO2composite nanoparticles have been prepared by sol-gel method and characterized by the techniques such as XRD, SEM and DRS. The photocatalytic degradation of methylene blue (MB) in aqueous solution was used as a probe reaction to evaluate their photocatalytic activity. The matrix distortion of TiO2nano-particles increases after co-doping of Eu3+and Sm3+and a blue-shift of the absorption profile are clearly observed. The results show that co-doping of Eu3+and Sm3+inhibits the phase transformation of TiO2from anatase to rutile, decreases the diameter of TiO2nano-particles and significantly enhance the photocatalytic activity of TiO2. The Eu3+and Sm3+co-doped into TiO2nano-particles exert a synergistic effect on their photocatalytic activity.

Understanding Persistent Luminescence: Rare-Earth- and Eu2+-doped Sr2MgSi2O7

2014 ◽  
Vol 69 (2) ◽  
pp. 171-182 ◽  
Author(s):  
Mika Lastusaari ◽  
Högne Jungner ◽  
Aleksei Kotlov ◽  
Taneli Laamanen ◽  
Lucas C. V. Rodrigues ◽  
...  
Keyword(s):  
Rare Earth ◽  
Band Gap ◽  
Charge Compensation ◽  
Band Gap Energy ◽  
Persistent Luminescence ◽  
Excitation Spectra ◽  
Co Doping ◽  
The Individual ◽  
Initial Intensity ◽  
The Eu

Similar to many other Eu2+,RE3+-co-doped persistent luminescence materials, for Sr2MgSi2O7:Eu2+,RE3+ the initial intensity and duration of persistent luminescence was also found to depend critically on the rare-earth (RE) co-doping. An enhancement of 1 - 2 orders of magnitude in these properties could be obtained by Dy3+ co-doping whereas total quenching of persistent luminescence resulted from the use of Sm3+ and Yb3+. To solve this drastic disparity, the effects of the individual RE3+ ions were studied with thermoluminescence (TL) spectroscopy to derive information about the formation of traps storing the excitation energy. The charge compensation defects were concluded to be the origin of the complex TL glow curve structure. The tuning of the band gap of the Sr2MgSi2O7 host and especially the position of the bottom of the conduction band due to the Eu2+,RE3+ co-doping was measured with the synchrotron radiation vacuum UV (VUV) excitation spectra of the Eu2+ dopant. The model based on the evolution of the band gap energy with RE3+ co-doping was found to explain the intensity and duration of the persistent luminescence.

Synthesis of Novel High Silicate-Substituted Hydroxyapatite by Co-Substitution Mechanisms

2007 ◽  
Vol 330-332 ◽  
pp. 87-90 ◽  
Author(s):  
J.A. Stephen ◽  
J.M.S. Skakle ◽  
Iain R. Gibson
Keyword(s):  
Chemical Structure ◽  
Bone Repair ◽  
Unit Cell ◽  
Secondary Phases ◽  
Co Substitution ◽  
Phosphate Ions ◽  
Substitution Mechanism ◽  
Coupled Substitution ◽  
High Silicate

Silicate substituted hydroxyapatite bioceramics have been shown to enhance bone repair in vivo compared to hydroxyapatite (HA), although the amount of silicate ions that can be substituted alone into the hydroxyapatite structure is limited to approximately 5.2 wt%, or 1.6 wt% Si. This study describes the substitution of greater levels of silicate ions via co-substitution of silicate ions with trivalent yttrium ions, without resulting in the formation of any secondary phases. This substitution mechanism involves a coupled substitution of yttrium and silicate ions for calcium and phosphate ions, respectively, and enables a level of silicate substitution up to approximately 9 wt%. Two different substitution mechanisms result in subtle differences in the crystal structure. When the mechanism xY3+ + xSiO4 4- was used, a small decrease in the a-axis, but no change in the c-axis, of the unit cell compared to HA was observed. In contrast, when the mechanism x/2Y3+ + xSiO4 4- was used, a significant increase in the c-axis of the unit cell was observed, compared to HA. XRF analysis and FTIR spectroscopy supported the proposed substitution mechanisms. These novel substitution mechanisms not only enable greater levels of silicate-substitution in HA to be prepared, but also allow the production of compositions with the same level of silicate substitution, and with subtle differences in chemical structure.

Effective blue-violet photoluminescence through lanthanum and fluorine ions co-doping for CsPbCl3 perovskite quantum dots

Nanoscale ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 2484-2491 ◽  
Author(s):  
Yue Zhai ◽  
Xue Bai ◽  
Gencai Pan ◽  
Jinyang Zhu ◽  
He Shao ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Quantum Yield ◽  
Feasible Method ◽  
Co Doping ◽  
Photoluminescence Quantum Yield ◽  
Perovskite Quantum Dots ◽  
Fluorine Ions

Co-doping of cation (La3+) and anion (F−) ions is a feasible method to improve the optical properties of CsPbCl3 QDs, and high photoluminescence quantum yield of 36.5% is achieved in CsPb(Cl0.7F0.3)3:La3+ QDs.

Stabilization of Eu3+ under a reductive atmosphere by the Al3+ co-doping of Sr2SiO4:Eu2+/Eu3+

RSC Advances ◽  
2016 ◽  
Vol 6 (53) ◽  
pp. 48001-48008 ◽  
Author(s):  
Karol Szczodrowski ◽  
Justyna Barzowska ◽  
Natalia Górecka ◽  
Marek Grinberg
Keyword(s):  
Concentration Ratio ◽  
Oxidation States ◽  
Co Doping ◽  
Aluminum Ions ◽  
Reductive Atmosphere ◽  
The Eu

The incorporation of aluminum ions into the Sr2SiO4:Eu causes the stabilization of the Eu3+ ions under reductive atmosphere and concentration ratio of europium in both oxidation states ([Eu3+]/[Eu2+]) can be controlled by changing the Al3+ content.

Emission Spectra of Zinc Oxychloride Tellurite Glass: Effects of Eu3+/Sm3+ Co-Doping

2011 ◽  
Vol 181-182 ◽  
pp. 451-454
Author(s):  
M.R. Sahar ◽  
R. Arifin ◽  
S.K. Ghoshal
Keyword(s):  
Tellurite Glass ◽  
Emission Spectra ◽  
Excitation Wavelength ◽  
Co Doping ◽  
Absorption Energy ◽  
Doped Glasses ◽  
Doped Glass ◽  
Co Doped ◽  
Resonance Transfer ◽  
The Eu

Eu3+or/and Sm3+co-doped glasses based on TeO2-ZnO-ZnCl2-Li2O are prepared using the melt quenching technique and the effects of co-doping on the emission spectra of these glasses are examined. The Sm3+doped glass under 403 nm excitations show emission bands around 561, 598 and 642 nm corresponding to the transitions of4G5/2→6H5/2,4G5/2→6H7/2and4G5/2→6H9/2respectively. Whereas, in Eu3+doped glass under 397 nm excitation emission bands appear around 553, 586, 613, 650 and 699 nm that corresponds to the transitions of5D1→7F2,5D0→7F1,5D0→7F2,5D0→7F3and5D0→7F4. In addition, the emission spectra of the Eu3+/Sm3+co-doped glass under 482 nm excitation consists of five bands in which three are contributed by Sm3+at 561, 598 and 642 nm and two by Eu3+at 613 nm and 699 nm respectively. Surprisingly, the emission bands of Eu3+are still observed in the emission spectra of Sm3+for the Eu3+/Sm3+co-doped glasses despite the absence of the excitation wavelength 482 nm in the absorption and excitation domain of Eu3+. This observation is attributed to the partial resonance transfer of the absorption energy from Sm3+to the Eu3+ions.

scholarly journals Diarylphosphate as a New Route for Design of Highly Luminescent Ln Complexes

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3934
Author(s):  
Alexey E. Kalugin ◽  
Mikhail E. Minyaev ◽  
Lada N. Puntus ◽  
Ilya V. Taydakov ◽  
Evgenia A. Varaksina ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Quantum Yield ◽  
Coordination Sphere ◽  
Near Infrared ◽  
Photophysical Properties ◽  
Transfer Scheme ◽  
Chloride Complexes ◽  
Very High ◽  
Bright Luminescence ◽  
The Eu

Organophosphate-chloride complexes [{(2,6-iPr2C6H3-O)2POO}2LnCl(CH3OH)4]·2CH3OH, Ln = Nd (1), Eu (2), Gd (3), and Tb (4) have been obtained and structurally characterized. Their reaction with 2,2′:6′,2″-terpyridine leads to the formation of 1:1 adducts ([{(2,6-iPr2C6H3-O)2POO}2LnCl(terpy)(H2O)2(CH3OH)], Ln = Eu (5), Gd (6), Tb (7) with exception of Nd, where tris-diisopropylphenylphosphate complex [{(2,6-iPr2C6H3-O)2POO}3Nd) (terpy)(H2O)(CH3OH)] (8) was obtained due to the ligand metathesis. A bright luminescence observed for the Eu and Tb organophosphate complexes is the first example of an application of organophosphate ligands for 4f-ions luminescence sensitization. Photophysical properties of all complexes were analyzed by optical spectroscopy and an energy transfer scheme was discussed. A combination of two types of ligands into the coordination sphere (phosphate and phenanthroline) allows designing the Eu surrounding with very high intrinsic quantum yield QEuEu (0.92) and highly luminescent Ln complexes for both visible and near-infrared (NIR) regions.

scholarly journals Syntheses and Characterization of Novel Perovskite-Type LaScO3-Based Lithium Ionic Conductors

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 299
Author(s):  
Guowei Zhao ◽  
Kota Suzuki ◽  
Masaaki Hirayama ◽  
Ryoji Kanno
Keyword(s):  
Activation Energy ◽  
Ionic Conductivity ◽  
Structure Refinement ◽  
Compositional Analysis ◽  
Unit Cell ◽  
Phase Identification ◽  
Ionic Conductors ◽  
Co Doping ◽  
A Site ◽  
Perovskite Type

Perovskite-type lithium ionic conductors were explored in the (LixLa1−x/3)ScO3 system following their syntheses via a high-pressure solid-state reaction. Phase identification indicated that a solid solution with a perovskite-type structure was formed in the range 0 ≤ x < 0.6. When x = 0.45, (Li0.45La0.85)ScO3 exhibited the highest ionic conductivity and a low activation energy. Increasing the loading of lithium as an ionic diffusion carrier expanded the unit cell volume and contributed to the higher ionic conductivity and lower activation energy. Cations with higher oxidation numbers were introduced into the A/B sites to improve the ionic conductivity. Ce4+ and Zr4+ or Nb5+ dopants partially substituted the A-site (La/Li) and B-site Sc, respectively. Although B-site doping produced a lower ionic conductivity, A-site Ce4+ doping improved the conductive properties. A perovskite-type single phase was obtained for (Li0.45La0.78Ce0.05)ScO3 upon Ce4+ doping, providing a higher ionic conductivity than (Li0.45La0.85)ScO3. Compositional analysis and crystal-structure refinement of (Li0.45La0.85)ScO3 and (Li0.45La0.78Ce0.05)ScO3 revealed increased lithium contents and expansion of the unit cell upon Ce4+ co-doping. The highest ionic conductivity of 1.1 × 10−3 S cm−1 at 623 K was confirmed for (Li0.4Ce0.15La0.67)ScO3, which is more than one order of magnitude higher than that of the (LixLa1−x/3)ScO3 system.

Optical properties of undoped, Eu3+ doped and Li+ co-doped Y2Hf2O7 nanoparticles and polymer nanocomposite films

2020 ◽  
Vol 7 (2) ◽  
pp. 505-518 ◽  
Author(s):  
Santosh K. Gupta ◽  
Jose P. Zuniga ◽  
Maya Abdou ◽  
P. S. Ghosh ◽  
Yuanbing Mao
Keyword(s):  
Optical Properties ◽  
Quantum Yield ◽  
Polymer Nanocomposite ◽  
Nanocomposite Films ◽  
Asymmetry Ratio ◽  
Covalent Character ◽  
Co Doping ◽  
Concentration Asymmetry ◽  
Co Doped

Li+ co-doping of Y2Hf2O7:Eu3+ nanoparticles improve their quenching concentration, asymmetry ratio, quantum yield, and radioluminescence intensity due to the enhanced covalent character of Eu3+–O2− bonding.

scholarly journals 27Al MAS NMR spectroscopy study of Eu2+-doped and Dy3+-co-doped SrAl4O7

2020 ◽  
Vol 60 (2) ◽  
Author(s):  
Martynas Misevičius ◽  
Laurynas Dagys ◽  
Arūnas Maršalka ◽  
Kristina Kristinaitytė ◽  
Vytautas Balevičius
Keyword(s):  
Solid State ◽  
Pulse Sequences ◽  
Single Pulse ◽  
Local Environment ◽  
Mas Nmr ◽  
Strontium Aluminate ◽  
Co Doping ◽  
27Al Mas Nmr ◽  
Co Doped ◽  
The Eu

The Eu2+-doped strontium aluminate SrAl4O7 samples have shown the blue-green persistent luminescence at 490 nm while the co-doping with Dy3+ shifts the maximum of emission to 475 nm. Undoped, 3% Eu-doped and 6% Dy-co-doped SrAl4O7 samples were prepared by the solid state-reaction method and studied by the solid-state 27Al MAS NMR applying the single pulse-acquire and Hahn-echo pulse sequences. It was shown that the Eu2+ with Dy3+ ion doping did not affect the bulk structure as well as the local Al environment in SrAl4O7. This means that large shifts of the emission maximum cannot be caused by changes in the local environment upon the co-doping of SrAl4O7:Eu2+ with Dy3+. However, the spectral features observed in the range between the signals of 4- and 6-coordinated Al (20–40 ppm) indicate that certain phase imperfections are present in all studied samples, and most probably amorphous/glassy domains were formed. Note that such amount of phase impurities was not detected by standard XRD or FTIR methods. This has revealed the 27Al MAS NMR technique to be a very effective tool monitoring the phase perfectness in series of strontium aluminate samples.

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