Higher Intrinsic Quantum Yield of Eu3+-Doped Zn2sio4 Obtained by Sol-Gel Process, Calculated by Judd - Ofelt Theory

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Jefferson Luis Ferrari ◽  
Adriana Souza de Oliveira ◽  
Juliana Maria Martins Buarque ◽  
Luiz Fernando Cappa de Oliveira ◽  
Clebio Soares Nascimento Jr. ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Quantum Yield ◽  
Annealing Temperature ◽  
Sol Gel ◽  
High Symmetry ◽  
Ofelt Theory ◽  
Higher Symmetry ◽  
Molar Ratios ◽  
Sol Gel Process ◽  
Photoluminescent Materials

The sol-gel process allows the obtaining of Eu3+-doped Zn2SiO4with 1 mol% with different molar ratios between Zn2+ and Si4+. The materials reported here were obtained with a resistive furnace at 600, 900, 1000 and 1100°C degree, during 2 h. All the materials exhibited an intense photoluminescence emission with bands assigned to the Eu3+ transitions. Among the materials studied, the samples containing 70 and 80% of Si4+, exhibited higher Eu3+ lifetimes values. The predominance of the quartz phase decreases micro deformations and the location of the Eu3+ ions in higher symmetry sites, reducing the intensity of the photoluminescent materials. The increasing of annealing temperature contributes to the detrimental lifetime and luminescence materials due to the location of the Eu3+ in the site of high symmetry. Through Judd-Ofelt theory was possible to obtain higher values of intrinsic quantum yield (QLn Ln) between 32 and 66% dependent on the temperature of heat-treatment, in comparison with the same material reported in the literature. Keywords: Orthosilicates; Photoluminescence; Rare Earth; Europium;

Effect of Annealing temperature on the Structural and Magnetic Properties of TbxY3-xFe5O12(x = 0.0, 1.0, 2.0) Thin Films Prepared by Sol-Gel Process

2012 ◽  
Vol 501 ◽  
pp. 236-241 ◽  
Author(s):  
Ftema W. Aldbea ◽  
Noor Bahyah Ibrahim ◽  
Mustafa Hj. Abdullah ◽  
Ramadan E. Shaiboub
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Vibrating Sample Magnetometer ◽  
X Ray ◽  
Garnet Phase ◽  
Sol Gel Process ◽  
Amorphous Structures

Thin films nanoparticles TbxY3-xFe5O12 (x=0.0, 1.0, 2.0) were prepared by the sol-gel process followed by annealing process at various annealing temperatures of 700° C, 800° C and 900° C in air for 2 h. The results obtained from X-ray diffractometer (XRD) show that the films annealed below 900°C exhibit peaks of garnet mixed with small amounts of YFeO3 and Fe2O3. Pure garnet phase has been detected in the films annealed at 900°C. Before annealing the films show amorphous structures. The particles sizes measurement using the field emission scanning electron microscope (FE-SEM) showed that the particles sizes increased as the annealing temperature increased. The magnetic properties were measured at room temperature using the vibrating sample magnetometer (VSM). The saturation magnetization (Ms) of the films also increased with the annealing temperature. However, different behavior of coercivity (Hc) has been observed as the annealing temperature was increased.

Preparation of Macroprous C12A7 Mayenite Monoliths via a Sol-Gel Process with Nitrates as Precursors

2018 ◽  
Vol 768 ◽  
pp. 211-217 ◽  
Author(s):  
Rui Wang ◽  
Yu Kun Sun ◽  
Bao Jia Qi Jiang ◽  
Hui Yang ◽  
Xing Zhong Guo
Keyword(s):  
Heat Treatment ◽  
Phase Separation ◽  
Binary System ◽  
Propylene Oxide ◽  
Crystalline Phase ◽  
Sol Gel ◽  
Single Crystalline ◽  
Sol Gel Process

Macroporous Ca12Al14O33(C12A7) mayenite monoliths have been successfully prepared via a sol-gel process in the presence of propylene oxide (PO) and poly (ethyleneoxide) (PEO). Gelation of CaO-Al2O3binary system with nitrates salts as additional precursors is accelerated by PO as an acid scavenger, while PEO works as a phase separation inducer to mediate the phase separation of the system. Appropriate PO and PEO amounts allow the formation of monolithic xerogel with interconnected macropores and co-continuous skeletons. The resultant dried gels are amorphous and the single crystalline phase Ca12Al14O33mayenite forms after heat-treatment at 1100 °C in air, while the macrostructure is preserved with a porosity as high as 78% and smoother and denser skeletons.

scholarly journals Anodizing of Aluminum Coated with Zirconium Oxide by a Sol-Gel Process I. Effect of Heat Treatment on the Formation of the Anodic Oxide Film

1999 ◽  
Vol 67 (12) ◽  
pp. 1243-1248 ◽  
Author(s):  
Keiji WATANABE ◽  
Masatoshi SAKAIRI ◽  
Hideaki TAKAHASHI ◽  
Katsumi TAKAHIRO ◽  
Shinji NAGATA ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Oxide Film ◽  
Zirconium Oxide ◽  
Sol Gel ◽  
Anodic Oxide ◽  
Anodic Oxide Film ◽  
Sol Gel Process

Degradation of Phenol by Fe3+ Doped Nano-TiO2 Photocatalyst

2013 ◽  
Vol 859 ◽  
pp. 361-364 ◽  
Author(s):  
Jing Wang ◽  
Du Shu Huang ◽  
Wei Liu ◽  
Qing Shan Pan ◽  
Yong Min
Keyword(s):  
Degradation Rate ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Phenol Degradation ◽  
Nano Tio2 ◽  
Phenol Solution ◽  
Sol Gel Process ◽  
Two Peaks ◽  
Degradation Properties ◽  
Better Than

Degradation properties of phenol using nano-TiO2 as photocatalyst in aqueous solution were investigated. The effect of annealing temperature and ionic modification on the degradation was studied. The results showed that, 500 °C annealed TiO2 was better than 700 °C annealed. Photocatalyst nano-TiO2 material doped with Fe3+ was prepared quickly by sol-gel process and was used as photocatalyst to degrade phenol solution of 100mg/L under UV irradiation for 3 hours. UV spectrophotometer testing was made and found that two peaks at 210 nm and 270 nm were significantly become low, indicating that the phenol has been degraded. The phenol degradation rate was 94.18%.

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%.

Low Temperature Preparation of Mullite Whisker via Non-Hydrolytic Sol-Gel Process Combined with Molten Salt Method

2014 ◽  
Vol 936 ◽  
pp. 975-980 ◽  
Author(s):  
Kai Lin Fu ◽  
Wei Hui Jiang ◽  
Guo Feng ◽  
Jian Min Liu ◽  
Qian Wu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Low Temperature ◽  
Molten Salt ◽  
Sol Gel ◽  
Growth Direction ◽  
Treatment Temperature ◽  
Molten Salt Method ◽  
Low Temperature Preparation ◽  
Sol Gel Process ◽  
Temperature Preparation

Mullite whisker was prepared at low temperature via non-hydrolytic sol-gel (NHSG) process combined with molten salt method. The influence of heat treatment temperature was studied on the morphology and the microstructure of whisker, and its growth mechanism was also described. The results show that the mullite whisker appears at the lowest temperature of 750 °C, and optimized mullite whisker can be prepared at 850 °C with the growth direction of [00, whose diameter is in the range of 170~300 nm with the aspect ratio of >30.

Indium-Sensitized UV Photocatalysts Made from Alkali Titanate Microfibers

2009 ◽  
Vol 620-622 ◽  
pp. 651-654
Author(s):  
Leticia M. Torres-Martínez ◽  
Cecilia Sánchez-Trinidad ◽  
Vicente Rodríguez-González ◽  
Ricardo Gómez
Keyword(s):  
Heat Treatment ◽  
Annealing Time ◽  
Uv Light ◽  
Sol Gel ◽  
Dichlorophenoxyacetic Acid ◽  
Sem Images ◽  
Uv Light Irradiation ◽  
Heat Treated ◽  
Munk Function ◽  
Sol Gel Process

Indium-alkali microfibers doped ceramic were prepared by the sol-gel process. The gels preparation samples, were heat treated at 700°C for different length of time. The products were characterized by means of XRD, SEM-EDS and UV–Vis-DRS. The XRD showed the formation of the Na2Ti6O13 phase whose crystallinity depends on the annealing time. The band gap calculated from the UV–Vis Kubelka-Munk function shows very similar values (3.53-3.55 eV). The SEM images of the indium-alkali titanates show microfiber clumps morphologies of about 5 µm, and the EDS spectra show that In2O3 is on the Na2Ti6O13 surface. The results of the evaluation of the In-Na2Ti6O13 semiconductors in the 2, 4-dichlorophenoxyacetic acid (2, 4-D) photodecomposition under UV light irradiation, show that the photoactivity depends on the time of heat treatment of the samples.

Load TiO2 or TiO2-N on the Porous Carbon

2012 ◽  
Vol 512-515 ◽  
pp. 1686-1689
Author(s):  
Jie Chen ◽  
Le Fu Mei ◽  
Li Bing Liao
Keyword(s):  
Heat Treatment ◽  
Porous Carbon ◽  
Heat Treatment Temperature ◽  
Treatment Time ◽  
Sol Gel ◽  
Treatment Temperature ◽  
Heat Treatment Time ◽  
Sem Images ◽  
Soaking Time ◽  
Sol Gel Process

In this paper, porous carbon has been used to carry TiO2 and TiO2-N by a sol-gel process. The effect of soaking time, heat treatment temperature, and heat treatment time on the carrying efficiency have been studied. XRD experiments indicated that TiO2 and TiO2-N crystallized in anatase and rutile with the ratio of 3∶2. SEM images showed that island-like TiO2 and TiO2-N particles with diameters in the range of 1-5um, the biggest size is about 10um, were evenly coated on the surface of the porous carbon.

Synthesis and Characterization of SiO2@Y2MoO6:Eu3+ Core–Shell Structured Spherical Phosphors by Sol–Gel Process

2016 ◽  
Vol 16 (4) ◽  
pp. 3914-3920 ◽  
Author(s):  
G. Z Li ◽  
F. H Liu ◽  
Z. S Chu ◽  
D. M Wu ◽  
L. B Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Annealing Temperature ◽  
Uv Light ◽  
Sol Gel ◽  
Spherical Shape ◽  
Core Shell ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Average Size

SiO2@Y2MoO6:Eu3+ core–shell phosphors were prepared by the sol–gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as kinetic decays were used to characterize the resulting SiO2@Y2MoO6:Eu3+ core–shell phosphors. The XRD results demonstrated that the Y2MoO6:Eu3+ layers on the SiO2 spheres crystallized after being annealed at 700 °C and the crystallinity increased with raising the annealing temperature. The obtained core–shell phosphors have spherical shape with narrow size distribution (average size ca. 640 nm), non-agglomeration, and smooth surface. The thickness of the Y2MoO6:Eu3+ shells on the SiO2 cores could be easily tailored by varying the number of deposition cycles (70 nm for four deposition cycles). The Eu3+ shows a strong PL emission (dominated by 5D0–7F2 red emission at 614 nm) under the excitation of 347 nm UV light. The PL intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles.

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