Spherical SiO2 @ GdPO4 : Eu3+ Core–Shell Phosphors: Sol–Gel Synthesis and Characterization

2007 ◽  
Vol 7 (2) ◽  
pp. 542-548 ◽  
Author(s):  
Cuikun Lin ◽  
Bo Zhao ◽  
Zhenling Wang ◽  
Min Yu ◽  
Huan Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Low Voltage ◽  
Uv Light ◽  
Sol Gel ◽  
Emission Spectra ◽  
Core Shell ◽  
Time Resolved ◽  
Potential Applications ◽  
Ft Ir ◽  
Red Luminescence

Nanocrystalline GdPO4 : Eu3+ phosphor layers were coated on non-aggregated, monodisperse and spherical SiO2 particles by Pechini sol–gel method, resulting in the formation of core–shell structured SiO2 @ GdPO4 : Eu3+ particles. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL), low-voltage cathodoluminescence (CL), time-resolved PL spectra and lifetimes were used to characterize the core–shell structured materials. Both XRD and FT-IR results indicate that GdPO4 layers have been successfully coated on the SiO2 particles, which can be further verified by the images of FESEM and TEM. Under UV light excitation, the SiO2 @ GdPO4 : Eu3+ phosphors show orange-red luminescence with Eu3+ 5D0–7F1 (593 nm) as the most prominent group. The PL excitation and emission spectra suggest that an energy transfer occurs from Gd3+ to Eu3+ in SiO2 @ GdPO4 : Eu3+ phosphors. The obtained core–shell phosphors have potential applications in FED and PDP devices.

Spherical SiO2 @ GdPO4 : Eu3+ Core–Shell Phosphors: Sol–Gel Synthesis and Characterization

2007 ◽  
Vol 7 (2) ◽  
pp. 542-548
Author(s):  
Cuikun Lin ◽  
Bo Zhao ◽  
Zhenling Wang ◽  
Min Yu ◽  
Huan Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Low Voltage ◽  
Uv Light ◽  
Sol Gel ◽  
Emission Spectra ◽  
Core Shell ◽  
Time Resolved ◽  
Potential Applications ◽  
Ft Ir ◽  
Red Luminescence

Nanocrystalline GdPO4 : Eu3+ phosphor layers were coated on non-aggregated, monodisperse and spherical SiO2 particles by Pechini sol–gel method, resulting in the formation of core–shell structured SiO2 @ GdPO4 : Eu3+ particles. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL), low-voltage cathodoluminescence (CL), time-resolved PL spectra and lifetimes were used to characterize the core–shell structured materials. Both XRD and FT-IR results indicate that GdPO4 layers have been successfully coated on the SiO2 particles, which can be further verified by the images of FESEM and TEM. Under UV light excitation, the SiO2 @ GdPO4 : Eu3+ phosphors show orange-red luminescence with Eu3+ 5D0–7F1 (593 nm) as the most prominent group. The PL excitation and emission spectra suggest that an energy transfer occurs from Gd3+ to Eu3+ in SiO2 @ GdPO4 : Eu3+ phosphors. The obtained core–shell phosphors have potential applications in FED and PDP devices.

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.

scholarly journals Preparation and Photocatalytic Activity of Magnetic Fe3O4/SiO2/TiO2Composites

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Rijing Wang ◽  
Xiaohong Wang ◽  
Xiaoguang Xi ◽  
Ruanbing Hu ◽  
Guohua Jiang
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Separation And Purification ◽  
X Ray Diffraction ◽  
Magnetic Composites ◽  
X Ray ◽  
Structure And Morphology ◽  
Transmission Electron ◽  
Potential Applications ◽  
Ft Ir

A simple sol-gel method was used to prepare magnetic Fe3O4/SiO2/TiO2composites with core-shell structure. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) have been applied to investigate the structure and morphology of the resultant composites. The obtained composites showed excellent magnetism and higher photodegradation ability than pure TiO2. The photocatalytic mechanism was also discussed. The magnetic composites should be extended to various potential applications, such as photodegradation, catalysis, separation, and purification processes.

Sub-Micrometer SiO2@ZnMoO4:Tb3+ Core-Shell Phosphors: Sol-Gel Synthesis and Characterization

2013 ◽  
Vol 800 ◽  
pp. 436-439
Author(s):  
Hu Yang ◽  
Xiao Bo Zhang ◽  
Juan Li ◽  
Yu Jun Lu
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Emission Spectra ◽  
Green Emission ◽  
Core Shell ◽  
Uniform Size ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Shell Particles ◽  
Sol Gel Synthesis

ZnMoO4:Tb3+ phosphor layers were grown on monodisperse SiO2 particles through a simple sol-gel method, resulting in the formation of core-shell structured SiO2@ZnMoO4:Tb3+ sub-microspheres. The resulting SiO2@ZnMoO4:Tb3+ core-shell particles were characterized by powder X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), transmission electron microscopy(TEM) and photoluminescence(PL). SEM and TEM analysis indicates that the obtained sub-microspheres have a uniform size distribution and obvious core-shell structure. SiO2@ZnMoO4:Tb3+ sub-microspheres show strong green emission under ultraviolet(275nm) illumination and the emission spectra are dominated by a 5D4→7F5 transition of Tb3+(543nm,green) from the ZnMoO4:Tb3+ shells. The optimum concentration for Tb3+ was determined to be 5 mol% of Zn2+ in ZnMoO4 host shells.

Bioactive and Biocompatible Silica/Pseudowollastonite Aerogels

2014 ◽  
Vol 96 ◽  
pp. 21-26 ◽  
Author(s):  
P.J. Reséndiz-Hernández ◽  
D.A. Cortés-Hernández ◽  
Juan Méndez Nonell ◽  
J.C. Escobedo-Bocardo
Keyword(s):  
Bone Tissue ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Ambient Pressure Drying ◽  
Bone Tissue Regeneration ◽  
Tissue Formation ◽  
Potential Applications ◽  
Ft Ir ◽  
Bone Tissue Formation

Silica aerogels have attracted increasingly more attention due to their extraordinary properties and their existing and potential applications in a wide variety of technological areas. Materials that promote bone-tissue formation at their surface and bond to osseous tissues when implanted are called bioactive, such as pseudowollastonite particles. In this work, the synthesis of aerogels with pseudowollastonite particles was performed. The synthesis involved the preparation of an alcogel by a two step sol-gel route followed by ambient pressure drying. To promote a higher bioactivity the obtained aerogels were then biomimetically treated using simulated body fluids, SBF and 1.5 SBF. A high bioactivity was demonstrated by FT-IR, SEM, EDS, and XRD. The in vitro biocompatibility was assessed by testing cytotoxicity using rat osteoblasts cultures. The results obtained indicate that these materials are highly potential aerogels for bone tissue regeneration.

Sol-gel synthesis, characterisation, and photocatalytic activity of porous spinel Co3O4 nanosheets

2014 ◽  
Vol 68 (8) ◽  
Author(s):  
Manoj Pudukudy ◽  
Zahira Yaakob
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Surface Area ◽  
Uv Light ◽  
Average Pore Size ◽  
Sol Gel ◽  
Spherical Particles ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
Oriented Growth

AbstractMesoporous spinel Co3O4 nanosheets were synthesised via a simple sol-gel route using the Pluronic P123 triblock copolymer as the stabilising agent. Their structural, morphological, and textural properties were characterised. FTIR spectrum revealed the formation of cobalt oxide without any surface adsorbed impurities. Face centered cubic phase of spinel Co3O4 with the mean crystalline size of 26 nm was assigned by the X-ray diffraction analysis without the formation of other phases. Porous nanosheets and cave-like morphologies were identified from the scanning electron microscopy (SEM) images. Highly agglomerated more or less spherical particles with well separated lattice fringes, representing the oriented growth of nanocrystals, were noticed on the transmission electron microscopy photographs. Surface area analysis revealed that the spinel has high surface area of about 25 m2 g−1 with monomodal mesoporosity. The average pore size distribution was found to be about 15.8 nm. The as-prepared spinel photocatalyst showed a mild photocatalytic activity in the degradation of methylene blue (2.5 mg L−1) under UV light irradiation with air as the oxidising agent. Photocatalytic activity of the as-prepared reusable Co3O4 was found to be higher than that of the commercial spinel powder.

scholarly journals Lead-Free BNT–BT0.08/CoFe2O4 Core–Shell Nanostructures with Potential Multifunctional Applications

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 672
Author(s):  
Marin Cernea ◽  
Roxana Radu ◽  
Harvey Amorín ◽  
Simona Gabriela Greculeasa ◽  
Bogdan Stefan Vasile ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Molar Ratio ◽  
Transmission Electron Microscopy Data ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Two Phase ◽  
X Ray ◽  
Shell Nanostructures

Herein we report on novel multiferroic core–shell nanostructures of cobalt ferrite (CoFe2O4)–bismuth, sodium titanate doped with barium titanate (BNT–BT0.08), prepared by a two–step wet chemical procedure, using the sol–gel technique. The fraction of CoFe2O4 was varied from 1:0.5 to 1:1.5 = BNT–BT0.08/CoFe2O4 (molar ratio). X–ray diffraction confirmed the presence of both the spinel CoFe2O4 and the perovskite Bi0.5Na0.5TiO3 phases. Scanning electron microscopy analysis indicated that the diameter of the core–shell nanoparticles was between 15 and 40 nm. Transmission electron microscopy data showed two–phase composite nanostructures consisting of a BNT–BT0.08 core surrounded by a CoFe2O4 shell with an average thickness of 4–7 nm. Cole-Cole plots reveal the presence of grains and grain boundary effects in the BNT–BT0.08/CoFe2O4 composite. Moreover, the values of the dc conductivity were found to increase with the amount of CoFe2O4 semiconductive phase. Both X-ray photoelectron spectroscopy (XPS) and Mössbauer measurements have shown no change in the valence of the Fe3+, Co2+, Bi3+ and Ti4+ cations. This study provides a detailed insight into the magnetoelectric coupling of the multiferroic BNT–BT0.08/CoFe2O4 core–shell composite potentially suitable for magnetoelectric applications.

scholarly journals Zn Doped α-Fe2O3: An Efficient Material for UV Driven Photocatalysis and Electrical Conductivity

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 273 ◽  
Author(s):  
Suman ◽  
Surjeet Chahal ◽  
Ashok Kumar ◽  
Parmod Kumar
Keyword(s):  
Band Gap ◽  
Room Temperature ◽  
Uv Light ◽  
Sol Gel ◽  
High Energy ◽  
Lattice Parameter ◽  
Dielectric Behavior ◽  
Energy Storage Devices ◽  
Vis Spectroscopy ◽  
Potential Applications

Zinc (Zn) doped hematite (α-Fe2O3) nanoparticles with varying concentrations (pure, 2%, 4% and 6%) were synthesized via sol-gel method. The influence of divalent Zn ions on structural, optical and dielectric behavior of hematite were studied. X-ray diffraction (XRD) pattern of synthesized samples were indexed to rhombohedral R3c space group of hematite with 14–21 nm crystallite size. The lattice parameter (a and c) values increase upto Zn 4% and decrease afterwards. The surface morphology of prepared nanoparticles were explored using transmission electron microscopy (TEM). The band gap measured from Tauc’s plot, using UV-Vis spectroscopy, showed reduction in its values upto Zn 4% and the reverse trend was obtained in higher concentrations. The dielectric properties of pure and Zn doped hematite were investigated at room temperature and followed the same trends as that of XRD parameters and band gap. Photocatalytic properties of nanoparticles were performed for hazardous Rose bengal dye and showed effective degradation in the presence of UV light. Hence, Zn2+ doped hematite can be considered as an efficient material for the potential applications in the domain of photocatalysis and also higher value of dielectric constant at room temperature makes them applicable in high energy storage devices.

scholarly journals Combining the Photocatalysis and Absorption Properties of Core-Shell Cu-BTC@TiO2 Microspheres: Highly Efficient Desulfurization of Thiophenic Compounds from Fuel

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2209 ◽  
Author(s):  
Jing Liu ◽  
Xiao-Min Li ◽  
Jing He ◽  
Lu-Ying Wang ◽  
Jian-Du Lei
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Photocatalytic Oxidation ◽  
Uv Light ◽  
Sulfur Removal ◽  
Oxidation Products ◽  
Core Shell ◽  
Adsorptive Desulfurization ◽  
X Ray ◽  
Tio2 Microspheres

A core-shell Cu-benzene-1,3,5-tricarboxylic acid (Cu-BTC)@TiO2 was successfully synthesized for photocatalysis-assisted adsorptive desulfurization to improve adsorptive desulfurization (ADS) performance. Under ultraviolet (UV) light irradiation, the TiO2 shell on the surface of Cu-BTC achieved photocatalytic oxidation of thiophenic S-compounds, and the Cu-BTC core adsorbed the oxidation products (sulfoxides and sulfones). The photocatalyst and adsorbent were combined using a distinct core-shell structure. The morphology and structure of the fabricated Cu-BTC@TiO2 microspheres were verified by scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, X-ray powder diffraction, nitrogen adsorption-desorption and X-ray photoelectron spectroscopy analyses. A potential formation mechanism of Cu-BTC@TiO2 is proposed based on complementary experiments. The sulfur removal efficiency of the microspheres was evaluated by selective adsorption of benzothiophene (BT) and dibenzothiophene (DBT) from a model fuel with a sulfur concentration of 1000 ppmw. Within a reaction time of 20 min, the BT and DBT conversion reached 86% and 95%, respectively, and achieved ADS capacities of 63.76 and 59.39 mg/g, respectively. The BT conversion and DBT conversion obtained using Cu-BTC@TiO2 was 6.5 and 4.6 times higher, respectively, than that obtained using Cu-BTC. A desulfurization mechanism was proposed, the interaction between thiophenic sulfur compounds and Cu-BTC@TiO2 microspheres was discussed, and the kinetic behavior was analyzed.

Investigation of Phase Transformation and Structure Evolution of Electrospun Copper Oxide Nanofibers during Thermal Annealing

2011 ◽  
Vol 471-472 ◽  
pp. 792-797
Author(s):  
Dariush Jafar Khadem ◽  
Zahira Yaakob ◽  
Samaneh Shahgaldi ◽  
Wan Ramli Wan Daud ◽  
Edy Herianto Majlan
Keyword(s):  
Electron Microscopy ◽  
Copper Oxide ◽  
Sol Gel ◽  
Building Blocks ◽  
Structure Evolution ◽  
Gravimetric Analysis ◽  
Effective Parameters ◽  
Transmission Electron ◽  
Electrospinning Method ◽  
Potential Applications

One-dimensional nanostructures, like nanofibers, nanobelts, nanotubes, nanorods have been regarded as a new class of nanomaterials that have been attracted as the most promising building blocks for verity applications in the last few years. As one type of important structures with intensive research efforts have been devoted to the production and investigation of the metal oxides. Metal oxide nanofibers have different potential to play an essential role in a series of application such as optics, nanoelectronics, catalysts, sensors, storage, optoelectonics, and full cell. Copper oxide nanostructures is a promising semiconductor material with potential applications in photochemical, electrochemical, electrochromic especially in water splitting, catalysts, and fabrication of photovoltaic devices. In this paper electrospinning method via sol-gel was used to fabricate copper oxide nanofibers. Copper oxide nanofibers with different morphology were synthesized by different calcinations temperature. In this paper, effective parameters such as voltage, concentration of precursor and different calcinations temperature were characterized by thermal gravimetric analysis, scanning electron microscopy (SEM), Transmission electron microscopy, x-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR) and Brunauer Emmett and Teller (BET).

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