scholarly journals Sol-Gel Derived Eu3+-Doped Gd2Ti2O7Pyrochlore Nanopowders

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Sanja Ćulubrk ◽  
Željka Antić ◽  
Vesna Lojpur ◽  
Milena Marinović-Cincović ◽  
Miroslav D. Dramićanin
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Changes ◽  
Sol Gel ◽  
Pyrochlore Phase ◽  
Structural Defects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Synthesis

Herein we presented hydrolytic sol-gel synthesis and photoluminescent properties of Eu3+-doped Gd2Ti2O7pyrochlore nanopowders. According to Gd2Ti2O7precursor gel thermal analysis a temperature of 840°C is identified for the formation of the crystalline pyrochlore phase. Obtained samples were systematically characterized by powder X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence spectroscopy. The powders consist of well-crystalline cubic nanocrystallites of approximately 20 nm in size as evidenced from X-ray diffraction. The scanning and transmission electron microscopy shows that investigated Eu3+-doped Gd2Ti2O7nanopowders consist of compact, dense aggregates composed entirely of nanoparticles with variable both shape and dimension. The influence of Eu3+ions concentration on the optical properties, namely, photoluminescence emission and decay time, is measured and discussed. Emission intensity as a function of Eu3+ions concentration shows that Gd2Ti2O7host can accept Eu3+ions in concentrations up to 10 at.%. On the other hand, lifetime values are similar up to 3 at.% (~2.7 ms) and experience decrease at higher concentrations (2.4 ms for 10 at.% Eu3+). Moreover, photoluminescent spectra and lifetime values clearly revealed presence of structural defects in sol-gel derived materials proposing photoluminescent spectroscopy as a sensitive tool for monitoring structural changes in both steady state and lifetime domains.

Pure and Ca-doped LaCoO3 Nanopowders: Sol-Gel Synthesis, Characterization and Magnetic Properties

2004 ◽  
Vol 848 ◽  
Author(s):  
Lidia Armelao ◽  
Davide Barreca ◽  
Gregorio Bottaro ◽  
Andrea Caneschi ◽  
Claudio Sangregorio ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Properties ◽  
Chemical Composition ◽  
Auger Electron ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Synthesis

ABSTRACTThis work is focused on the sol-gel synthesis of pure and Ca-doped LaCoO3 nanopowders. The samples were prepared starting from methanolic solutions of cobalt (II) acetate (Co(CH3COO)2·4H2O), lanthanum (III) nitrate (La(NO3)3·6H2O) and calcium (II) acetate (Ca(CH3COO)2·H2O). After solvent evaporation, the obtained powders were dried under vacuum and subsequently treated in air up to 1273 K. The system evolution under thermal annealing was studied by X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM), while the chemical composition was analyzed by X-ray Photoelectron (XPS) and X-ray Excited Auger electron (XE-AES) spectroscopies. The temperature and field dependence of the magnetic properties of the Ca-doped samples were investigated, and compared to those of the corresponding pure LaCoO3 powders.

The structural changes of polycrystalline film C60/C70: Ni caused by Ni diffusion

1996 ◽  
Vol 11 (12) ◽  
pp. 3146-3151 ◽  
Author(s):  
E. Czerwosz ◽  
P. Byszewski ◽  
R. Diduszko ◽  
H. Wronka ◽  
P. Dluźewski ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Structural Changes ◽  
Thermal Conditions ◽  
Vacuum Deposition ◽  
X Ray Diffraction ◽  
Polycrystalline Structure ◽  
X Ray ◽  
Transmission Electron

C60/C70: Ni films with 1.5 wt. % Ni concentration obtained by vacuum deposition under different thermal conditions have been investigated. The structural changes of the layers were investigated by transmission electron microscopy, electron and x-ray diffraction, and Raman spectroscopy. The polycrystalline structure was detected for the layers grown at approximately 450 K on the substrate. At elevated temperature and maintained temperature gradient on the substrate during the process, the changes of the layer's structure and the formation of Ni microcrystals were observed. The Ni microcrystals (5–10 nm in the diameter) and the elongated shapes dimensioned 10 × 150 nm were perceived.

Sol-gel processing of nanocrystalline haematite thin films

1997 ◽  
Vol 12 (6) ◽  
pp. 1441-1444 ◽  
Author(s):  
L. Armelao ◽  
A. Armigliato ◽  
R. Bozio ◽  
P. Colombo
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Single Particles ◽  
X Ray ◽  
Transmission Electron ◽  
Gel Processing

The microstructure of Fe2O3 sol-gel thin films, obtained from Fe(OCH2CH3)3, was investigated by x-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. Samples were nanocrystalline from 400 °C to 1000 °C, and the crystallized phase was haematite. In the coatings, the α–Fe2O3 clusters were dispersed as single particles in a network of amorphous ferric oxide.

Controlled Fabrication and Properties of Ce0.5Zr0.5O 2 Solid Solutions

2011 ◽  
Vol 295-297 ◽  
pp. 1414-1417
Author(s):  
Zhi Fang Zhang ◽  
Fang Yan Du ◽  
Xiang Rong Ma
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Solid Solutions ◽  
Sol Gel ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcination Temperatures ◽  
Transmission Electron ◽  
Pore Size Distributions

The nanocrystals Ce0.5Zr0.5O2 solid solutions with various morphologies and crystal structures have been synthesized via a modified sol-gel method assisted with a template. Aerosol OT and/or ionic liquids ([MMIM]Cl] and [BMIM]Cl]) was used as a template. The characterization results of the X-ray diffraction, transmission electron microscopy and N2 adsorption at 77 K indicate that the physical properties of the solid solutions were significantly affected by the templates used and the calcination temperatures. The Ce0.5Zr0.5O2 calcined at 773 K possessed bimodal mesopores, narrow pore size distributions, and tetragonal phase.

Transmission electron microscopy of hexadecyltrimethylammonium-exchanged smectite

Clay Minerals ◽  
2002 ◽  
Vol 37 (3) ◽  
pp. 465-471 ◽  
Author(s):  
Seung Yeop Lee ◽  
Soo Jin Kim
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Changes ◽  
Structural Features ◽  
Morphological Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Heterogeneity ◽  
Transmission Electron ◽  
Lattice Distortions

AbstractThe morphological and structural changes in smectite caused by hexadecyltrimethylammonium (HDTMA) treatment were studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The HDTMA-exchanged smectite shows not only morphological features such as irregular, wavy surface with curled edges, but also structural features such as large d-spacings (20 – 26 Å ) and lattice distortions. The surface morphological heterogeneity is assumed to be related to the inhomogeneous intercalation of HDTMA cations into the interlayer of smectite.

scholarly journals Obtaining and Characterization of TiO2-GO Composites for Photocatalytic Applications

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
D. K. Calvo Ramos ◽  
M. Vega González ◽  
R. A. Esparza Muñóz ◽  
J. Santos Cruz ◽  
F. J. De Moure-Flores ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Uv Radiation ◽  
Uv Light ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

Titanium dioxide (TD) and graphene oxide (GO) were synthesized by sol-gel and improved Hummers method, respectively. This study shows the results of the incorporation through four different conditions (sol-gel, sol-gel and ultrasonic, annealed, and UV radiation, C1 to C4, respectively). It was observed that a homogeneous incorporation of TD on sheets of GO was obtained satisfactorily. The composites of TiO2/GO were characterized using different techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and infrared spectroscopy (IR). The photocatalytic activity of the composites was determined from the degradation of the dye azo tartrazine using UV and solar radiation. The best incorporation of TD nanoparticles on GO was obtained with condition C3 (thermal incorporation method) at a temperature of 65°C. This shows a uniformity in the size and shape of the TD as well as an excellent adherence to the sheet of GO. This addition is accomplished by ionic bonding in the presence of electrostatic Coulomb forces. The C3 composite degraded the tartrazine dye using UV radiation and sunlight. With the latter, the degradation time was three times faster than using UV light.

Nanostructured red-emitting MgGa2O4:Eu3+ phosphors

2004 ◽  
Vol 19 (5) ◽  
pp. 1504-1508 ◽  
Author(s):  
Bin-Siang Tsai ◽  
Yen-Hwei Chang ◽  
Yu-Chung Chen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sol Gel ◽  
Photoluminescence Intensity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Gel Technique ◽  
Red Luminescence ◽  
20 Nm

Nano-grained phosphors of Eu3+-doped MgGa2O4 crystallites were prepared by sol-gel technique. The characterization and optical properties of luminescent MgGa2O4:Eu3+ powders have been investigated. The dried sol-gel powders were calcined in air at different temperature from 600 to 1000 °C for 5 h. The x-ray diffraction profiles showed that the MgGa2O4:Eu3+ powders began to crystallize around 600 °C and formed stable MgGa2O4 phase in the temperature range of 600–900 °C. The transmission electron microscopy morphology observations revealed that the fired powders exhibit small grain size less than 20 nm. In the PL studies, under ultraviolet (394 nm) excitation, the calcined powders emitted bright red luminescence (615 nm, 5D0→7F2), and the powders fired at 900 °C were found to have the maximum photoluminescence intensity. The quenching concentration of Eu3+ in MgGa2O4 crystallites was also indicated to be about 5∼6 mol%.

Facile Sol-Gel Synthesis of Mesoporous TiO2 in Ionic Liquids

2013 ◽  
Vol 389 ◽  
pp. 53-56
Author(s):  
Shu Guo ◽  
Sheng Xu Lu ◽  
Hui Ding ◽  
Zai Feng Shi
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Sol Gel ◽  
Rutile Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carboxylate Groups ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Sol Gel Synthesis

The mesoporous TiO2 particles was conveniently prepared in a room temperature ionic liquid (RTILs) of 1, 3-di-(3-propionyloxy) imdazolium tetrafluoroborate [DiprCOOBF4 system. The obtained materials were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 adsorptiondesorption analysis. XRD patterns revealed that only rutile phase is formed in the RTILs. The TEM micrographs as well as N2 adsorptiondesorption measurements show that the prepared products exhibited wormlike pore structures. The FTIR (Fourier Transform Infrared Spectra) demonstrate the carboxylate groups attach via bidentate or bridging coordination to the TiO2 surface.

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