Synthesis and luminescence properties of colloidal lanthanide doped YVO4

2001 ◽  
Vol 667 ◽  
Author(s):  
Arnaud Huignard ◽  
Thierry Gacoin ◽  
Frédéric Chaput ◽  
Jean-Pierre Boilot ◽  
Patrick Aschehoug ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Room Temperature ◽  
Sol Gel ◽  
Precursor Solution ◽  
Silica Matrix ◽  
Luminescence Quantum Yield ◽  
Colloidal Solutions ◽  
Silicon Alkoxide ◽  
Crystalline Defects ◽  
Hydroxylated Surface

ABSTRACTAqueous colloidal solutions of well dispersed YVO4:Ln (Ln = Eu, Nd) nanoparticles are synthesized through precipitation reactions at room temperature. In the case of YVO4:Eu, a luminescence quantum yield of 15% is found, which is not as high as in the bulk due to the existence of residual crystalline defects and nonradiative relaxations from the hydroxylated surface. Appropriate hydrothermal annealing and deuteration of the surface allow to rise the yield up to 38%. Incorporation of the nanocrystals into a transparent silica matrix is achieved through preliminary coating of the particles with a functionnalized silicon alkoxide and further dispersion into a sol-gel precursor solution. Such sol-gel materials doped with YVO4:Nd nanocrystals are transparent and exhibit the typical emission at 1.06 μm of the Nd3+ ion.

Effect of Precursor Sol Ageing on Sol-Gel Derived Ruthenium Oxide Thin Films

1999 ◽  
Vol 606 ◽  
Author(s):  
S. Bhaskar ◽  
S. B. Majumder ◽  
P. S. Dobal ◽  
R. S. Katiyar ◽  
A. L. M. Cruz ◽  
...  
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Ruthenium Oxide ◽  
Precursor Solution ◽  
Silicon Substrates ◽  
Solution Deposition ◽  
Precursor Material ◽  
Afm Analysis

AbstractIn the present work we have optimized the process parameters to yield homogeneous, smooth ruthenium oxide (RuO2) thin films on silicon substrates by a solution deposition technique using RuCl3.×.H2O as the precursor material. Films were annealed in a temperature range of 300°C to 700°C, and it was found that RuO2 crystallizes at a temperature as low as 400°C. The crystallinity of the films improves with increased annealing temperature and the resistivity decreases from 4.86µΩ-m (films annealed at 400°C) to 2.94pµΩ (films annealed at 700°C). Ageing of the precursor solution has a pronounced effect on the measured resistivities of RuO2 thin films. It was found that the measured room temperature resistivities increases from 2.94µΩ-m to 45.7µΩ-m when the precursor sol is aged for aged 60 days. AFM analysis on the aged films shows that the grain size and the surface roughness of the annealed films increase with the ageing of the precursor solution. From XPS analysis we have detected the presence of non-transformed RuCl3 in case of films prepared from aged solution. We propose, that solution ageing inhibits the transformation of RuCl3 to RuO2 during the annealing of the films. The deterioration of the conductivity with solution ageing is thought to be related with the chloride contamination in the annealed films.

Facile synthesis of monodisperse SrAl2O4:Eu2+ cage-like microspheres with an excellent luminescence quantum yield

2018 ◽  
Vol 6 (13) ◽  
pp. 3346-3351 ◽  
Author(s):  
Jun Wan ◽  
Yuting Zhang ◽  
Yuan Wang ◽  
Ronghua Ma ◽  
Yimin Wu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Quantum Yield ◽  
Sol Gel ◽  
Subsequent Heat Treatment ◽  
Luminescence Quantum Yield ◽  
Facile Synthesis

SrAl2O4:Eu2+ cage-like microspheres are prepared by a sol–gel route and subsequent heat treatment. The optimum quantum yield of the cage-like microspheres is 94.94%.

Synthesis of Mn2+ Doped CdS Nanocrystals Embedded in a Sol-Gel Silica Matrix: Characterization of the Luminescence Activator

1996 ◽  
Vol 452 ◽  
Author(s):  
G. Counio ◽  
S. Esnouf ◽  
T. Gacoin ◽  
P. Barboux ◽  
A. Hofstaetter ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Quantum Yield ◽  
Sol Gel ◽  
Silica Matrix ◽  
Silica Xerogels ◽  
Cds Nanocrystals ◽  
Bright Luminescence

AbstractMn2+-doped CdS nanocrystals (1.2 to 2.4 nm in diameter) embedded in organic-inorganic silica xerogels have been synthesized. Extensive studies (EXAFS, ESR and ENDOR) allow us to localize the ions responsible for the bright luminescence observed in such materials (quantum yield of 7%). The average number of Mn2+ per nanocrystal is in the 0.2–0.8 range, and the emission arises from an energy transfer from surface trapped carriers to Mn2+ ions.

Facile synthesis of monodisperse YAG:Ce3+ microspheres with high quantum yield via an epoxide-driven sol–gel route

2017 ◽  
Vol 5 (35) ◽  
pp. 8952-8957 ◽  
Author(s):  
Yuting Zhang ◽  
Xvsheng Qiao ◽  
Jun Wan ◽  
Li-ang Wu ◽  
Bing Chen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Quantum Yield ◽  
Sol Gel ◽  
Subsequent Heat Treatment ◽  
Luminescence Quantum Yield ◽  
High Quantum Yield ◽  
Facile Synthesis ◽  
High Quantum ◽  
Reducing Atmosphere

Monodisperse YAG:Ce3+ microspheres have been synthesized through a fast epoxide-driven sol–gel route and subsequent heat treatment under a reducing atmosphere. The luminescence quantum yield of the 6 mol% Ce3+ ion doped YAG microspheres was more than 90%.

scholarly journals Thermal Conductivity of Pure Silica MEL and MFI Zeolite Thin Films

2010 ◽  
Author(s):  
Thomas Coquil ◽  
Laurent Pilon ◽  
Christopher M. Lew ◽  
Yushan Yan
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Room Temperature ◽  
Sol Gel ◽  
Silica Matrix ◽  
Simultaneous Increase ◽  
Crystallization Time ◽  
Mfi Zeolite ◽  
Relative Crystallinity ◽  
Pure Silica

This paper reports the room temperature cross-plane thermal conductivity of pure silica zeolite (PSZ) MEL and MFI thin films. PSZ MEL thin films were prepared by spin coating a suspension of MEL nanoparticles in 1-butanol solution onto silicon substrates followed by calcination and vapor-phase silylation with trimethylchlorosilane. The mass fraction of nanoparticles within the suspension varied from 16 to 55%. This was achieved by varying the crystallization time of the suspension. The thin films consisted of crystalline MEL nanoparticles embedded in a non-uniform and highly porous silica matrix. They featured porosity, relative crystallinity and MEL nanoparticles size ranging from 40 to 59%, 23 to 47% and 55 to 80 nm, respectively. PSZ MFI thin films were made by in-situ crystallization, were b-oriented, fully crystalline and had a 33% porosity. Thermal conductivity of the PSZ thin films was measured at room temperature using the 3ω method. The cross-plane thermal conductivity of the MEL thin films remained constant around 1.02 ± 0.10 Wm−1K−1 despite increases in (i) relative crystallinity, (ii) nanoparticle size and (iii) yield as the nanoparticle crystallization time increased. Indeed, the effect of increases in these parameters on the thermal conductivity was compensated by the simultaneous increase in porosity. PSZ MFI thin films were found to have the same thermal conductivity as MEL thin films even though they had smaller porosity. Finally, the average thermal conductivity of the PSZ films was three to five times larger than that reported for amorphous sol-gel mesoporous silica thin films with similar porosity and dielectric constant.

Spectroscopic Investigations of Neptunium's and Plutonium's Oxidation States in Sol-Gel Glasses as a Function of Initial Valence and Thermal History

1996 ◽  
Vol 465 ◽  
Author(s):  
N. A. Stump ◽  
R. G. Haire ◽  
S. Dai
Keyword(s):  
Oxidation State ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Sol Gel ◽  
Solidification Process ◽  
Silica Matrix ◽  
Oxidation States ◽  
Temperature Spectra ◽  
Gel Glasses ◽  
Starting Solutions

ABSTRACTSeveral oxidation states of neptunium and plutonium, Pu(III), Pu(IV), Pu(VI), Np(IV), Np(V), and Np(VI), were studied in glasses prepared by a sol-gel technology. The oxidation state of these actinides in the sol-gel product was examined by absorption spectroscopy after solidification, aging, and thermal treatment. The oxidation state of the actinides in the starting solutions was essentially maintained through the solidification process of the silica matrix. However, during densification and removal of residual solvents at elevated temperatures, both actinides converted eventually to their tetra valent states while in the different sol-gel products. This finding is in accord with reports that tetravalent states of plutonium and neptunium are acquired in glass products prepared by dissolution of the actinide in molten glasses. Comparisons between room temperature spectra obtained from neptunium and plutonium in heated sol-gel products and from molten glass products showed subtle differences that can be related to the metal ion's environments.

Investigation of NiO-Al2O3-SiO2 Properties via XRD, FTIR Techniques and Thermal Analysis

2019 ◽  
Vol 946 ◽  
pp. 134-138
Author(s):  
Elizaveta Antoshkina ◽  
Olga Rakova ◽  
Andrey Efremov
Keyword(s):  
Gas Sensors ◽  
Room Temperature ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Silica Matrix ◽  
Chemical Bonds ◽  
Potential Applications ◽  
Amorphous Structures ◽  
Ftir Technique ◽  
Xrd Patterns

Nowadays, nanostructures made on the basis of mixed oxides are of great interest for fundamental scientific and applied researches because of its potential applications, such as photo catalysts, luminophores, sensitive elements of gas sensors and vacuum sensors. The article describes nanostructural properties of NiO–Al2O3–SiO2 prepared by sol-gel method. Nanocomposites were obtained by mixing a solution of Si (OC2H5)4 (TEOS) as a SiO2 precursor with a solution containing Al (NO3)3 · 9H2O and Ni (NO3)2 · 6H2O. Ethanol was used as solvent. The gel was dried at room temperature and annealed in the 100–500 °C range. The behavior of chemical bonds is considered by using FTIR technique. Crystallization of NiO phase at 500 °C is observed in XRD patterns. Aluminum atoms are incorporated into silica matrix, which was confirmed by XRD. The amorphous structures which are desirable for next generations are formed at room temperature.

Improved Sol-Gel Materials for Efficient Solid State Dye Lasers

1993 ◽  
Vol 329 ◽  
Author(s):  
Michael Canva ◽  
Patrick Georges ◽  
Jean-Fran^ois Perelgritz ◽  
Alain Brun ◽  
Fréddric Chaput ◽  
...  
Keyword(s):  
Solid State ◽  
Physical Properties ◽  
Room Temperature ◽  
Sol Gel ◽  
Tunable Lasers ◽  
Optical Quality ◽  
Dye Lasers ◽  
Laser Dyes ◽  
Host Matrix ◽  
Host Matrices

AbstractPhotoresistant laser dyes were trapped in silica based xerogel host matrices to obtain solid state tunable lasers. For this purpose very dense xerogel samples with improved chemical and physical properties were prepared at room temperature by the sol-gel technology. The as-prepared materials were polished to obtain optical quality surfaces and were used as new lasing media.Lasing action of such different dyes as rhodamine, perylene and pyrromethene doping dense sol-gel matrices was demonstrated. Efficiencies of 30 % or lifetimes of more than 100,000 shots were achieved with different new ≤dye dopant/host matrix≥ couples. Their different performances are reviewed and discussed.

Macrocellular Titanosilicate Monoliths as Highly Efficient Structured Olefin Epoxidation Catalysts

2019 ◽  
Author(s):  
Valentin Smeets ◽  
Ludivine van den Biggelaar ◽  
Tarek Barakat ◽  
Eric M. Gaigneaux ◽  
Damien Debecker
Keyword(s):  
Sol Gel ◽  
Silica Matrix ◽  
Flow Mode ◽  
Tetrahedral Coordination ◽  
Excellent Performance ◽  
One Pot ◽  
Templating Method ◽  
Porous Texture ◽  
Internal Phase ◽  
Epoxidation Of Cyclohexene

Self-standing macrocellular titanosilicate monolith foams are obtained using a one-pot sol-gel route and show excellent performance in the epoxidation of cyclohexene. Thanks to the High Internal Phase Emulsion (HIPE) templating method, the materials feature a high void fraction, a hierarchically porous texture and good mechanical strength. Highly dispersed Ti species can be incorporated in tetrahedral coordination the silica matrix. These characteristics allow the obtained ‘SiTi(HIPE)’ materials to reach high catalytic turnover in the epoxidation of cyclohexene. The monoliths can advantageously be used to run the reaction in continuous flow mode.<br>

Nickel (II) and oxovanadium (IV) complexes supported on MCM-41 mesoporous and their application in catalytic selective sulfide and thiol oxidation

2020 ◽  
Vol 23 ◽  
Author(s):  
Mohsen Nikoorazm ◽  
Maryam Khanmoradi ◽  
Masoumeh Sayadian
Keyword(s):  
Catalytic Activity ◽  
Room Temperature ◽  
Sol Gel ◽  
Reaction Times ◽  
Significant Loss ◽  
Spectral Studies ◽  
High Catalytic Activity ◽  
Catalytic Systems ◽  
Solvent Free Conditions ◽  
Mcm 41

Introduction:: MCM-41 was synthesized using the sol-gel method. Then two new transition metal complexes of Nickel (II) and Vanadium (IV), were synthesized by immobilization of adenine (6-aminopurine) into MCM-41 mesoporous. The compounds have been characterized by XRD, TGA, SEM, AAS and FT-IR spectral studies. Using these catalysts provided an efficient and enantioselective procedure for oxidation of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides using hydrogen peroxide at room temperature. Materials and Methods:: To a solution of sulfide or thiol (1 mmol) and H2O2 (5 mmol), a determined amount of the catalyst was added. The reaction mixture was stirred at room temperature for the specific time under solvent free conditions. The progress of the reaction was monitored by TLC using n-hexane: acetone (8:2). Afterwards, the catalyst was removed from the reaction mixture by centrifugation and, then, washed with dichloromethane in order to give the pure products. Results:: All the products were obtained in excellent yields and short reaction times indicating the high activity of the synthesized catalysts. Besides, the catalysts can be recovered and reused for several runs without significant loss in their catalytic activity. Conclusion:: These catalytic systems furnish the products very quickly with excellent yields and VO-6AP-MCM-41 shows high catalytic activity compared to Ni-6AP-MCM-41.

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