scholarly journals Dibenzothiophene Hydrodesulfurization over P-CoMo on Sol-Gel Alumina Modified by La Addition. Effect of Rare-Earth Content

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 359 ◽  
Author(s):  
José Escobar ◽  
María C. Barrera ◽  
Jaime S. Valente ◽  
Dora A. Solís-Casados ◽  
Víctor Santes ◽  
...  
Keyword(s):  
Rare Earth ◽  
Sol Gel ◽  
Species Interaction ◽  
X Ray Diffraction ◽  
One Pot ◽  
Binary Matrices ◽  
La Addition ◽  
Coordination Change ◽  
Middle Distillates ◽  
Rare Earth Content

Alumina-lanthana (La at 1, 3, or 5 wt%) supports were prepared by sol-gel from Al alkoxide sol where La(NO3)3 was added. Annealed (550 °C) xerogels were characterized by N2 physisorption, thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy- energy dispersive spectroscopy (SEM-EDS), CO2-adsorption studied in IR region, Raman and ultraviolet-vis (UV-vis) spectroscopies. The texture of amorphous binary matrices of high La dispersion was adequate to applications in catalysts for middle distillates hydrodesulfurization (HDS). Generally, the amount and strength of surface basic sites increased with La content in solids. Mo (at 2.8 at. nm−2) and Co (at Co/(Co+Mo) = 0.3) were deposited over carriers by one-pot simultaneous impregnation in the presence of PO43− (P2O5/(NiO+MoO3) = 0.2 mass ratio). Calcined (400 °C) Co-Mo-P impregnated precursors had decreased basicity as to that of corresponding carriers, suggesting strong La-deposited species interaction. As La content in carriers increased Mo=O Raman stretching vibrations shifted to lower wave-numbers (949 to 935 cm−1) suggesting octahedral molybdates coordination change to tetrahedral. Although La at the lowest concentration (1 wt%) enhanced dibenzothiophene, HDS (~38% higher as to the Al2O3-supported formulation) desulfurization was significantly diminished at augmented content. Presence of hardly sulfidable tetrahedral Mo originated during impregnation at basic conditions in pores of La-modified carriers seemed to dictate observed behavior. Rare earth content in formulations enhanced selectivity to biphenyl.

X-ray structure determination of the rare earth oxides (Er1−uGdu)2O3applying the Rietveld method

2002 ◽  
Vol 35 (5) ◽  
pp. 577-580 ◽  
Author(s):  
Zein Heiba ◽  
Hasan Okuyucu ◽  
Y. S. Hascicek
Keyword(s):  
Rare Earth ◽  
Rietveld Method ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gel Technique ◽  
Average Size

Nanosized polycrystalline samples of (Er1−uGdu)2O3(0 ≤u≤ 1.0) were synthesized by a sol–gel technique. X-ray diffraction data were collected and the crystal structures were refined by the Rietveld method. All samples are found to have the same crystal system and formed solid solutions over the whole range ofu. The Er3+and Gd3+ions were randomly distributed over two cationic sites, 8band 24d, in the space groupIa\bar{3} (206) in all refined structures. The lattice parameter was found to vary non-linearly with the composition (u). The average microstrain and average crystallite size have been calculated from the Williamson–Hall plots for each sample. The average size ranges from 50 to 70 nm, and the microstrain from 0.4 to 1.7%.

Structural and Electrical Characterization of Rare Earth Doped Pb0.85La0.15TiO3 Ferroelectric Thin Films

1999 ◽  
Vol 596 ◽  
Author(s):  
P. S. Dobal ◽  
R. R. Das ◽  
B. Roy ◽  
R. S. Katiyar ◽  
S. Jain ◽  
...  
Keyword(s):  
Rare Earth ◽  
Transition Temperature ◽  
Sol Gel ◽  
Electrical Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Domain Wall Mobility ◽  
Wall Mobility

AbstractRare earth (Gd+3 and Ce+3) substitution on La+3 sites of the sol-gel prepared Pb0.85La0.15TiO3 films is studied using x-ray diffraction, atomic force microscopy, Raman scattering, and electrical characterization techniques. With increasing content of rare earths an increase in the lattice tetragonality was evidenced from x-ray data. Raman spectra obtained form Pb0.85La0.15-xCexTiO3 (x=0.0–0.07) and Pb0.85La0.15-xGdxTiO3 (x=0.0–0.15) films show features characteristics of PbTiO3 perovskite. Frequency variations of the lowest soft mode as a function of the composition x and temperature corraborate the increased tetragonality in these films. The ferroelectric transition temperature, dielectric constant, and coercive field was found to increase with Gd content. The phase transition temperature and polarization values increase up to 5 at.% Ce doping while they decrease above that composition due to the reduced domain wall mobility caused by Ce precipitation. A slight increase in the surface roughness was observed with increasing rare earth content in these films.

scholarly journals Rare Earth FreeZn3V2O8Phosphor with Controlled Microstructure and Its Photocatalytic Activity

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Hom Nath Luitel ◽  
Rumi Chand ◽  
Toshio Torikai ◽  
Mitsunori Yada ◽  
Takanori Watari
Keyword(s):  
Photocatalytic Activity ◽  
Rare Earth ◽  
Quantum Yield ◽  
Sol Gel ◽  
Emission Spectra ◽  
Host Lattice ◽  
X Ray Diffraction ◽  
Excitation Spectra ◽  
Visible Absorption ◽  
Pl Emission

Microsphere of rare earth free phosphor,Zn3V2O8, with broadband yellowish white emission was synthesized by combustion route and compared with the hydrothermal, sol-gel, and solid state reaction methods. The phosphor samples were characterized by X-ray diffraction and scanning electron microscopy. UV-visible absorption and photoluminescence (PL) emission and excitation spectra were investigated for these phosphors.Zn3V2O8phosphor containing 10 mol% of H3BO3flux exhibited enhanced PL emission showing broadband from 450 nm to 750 nm. Effect of stoichiometry of Zn and V on the host lattice and its effect on the PL emission spectra were studied. Series of Mg3V2O8,Ca3V2O8, and Sr3V2O8phosphors were also synthesized and compared to theZn3V2O8phosphor in terms of PL emission and internal quantum yield, and it was found thatZn3V2O8is the most efficient phosphor among the other phosphors studied with quantum yield of 60%. The visible light irradiated photocatalytic activity of these phosphors was investigated and it was found that the hydrothermalZn3V2O8exhibited enhanced activity.

Luminescence and X-ray Diffraction Studies of Rare Earth Doped Silica Sol-Gel Glass

2019 ◽  
Vol 25 (9) ◽  
pp. 255-262 ◽  
Author(s):  
Kurt R. Hoffman ◽  
Henok Alazar ◽  
Dan Boye ◽  
Ann Silversmith
Keyword(s):  
Rare Earth ◽  
Sol Gel ◽  
Silica Sol ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rare Earth Doped

Effects of Mg, Si and Multiple Rare Earth Addition on Microstructures of Al3Ti /A356 Composites

2012 ◽  
Vol 557-559 ◽  
pp. 244-248
Author(s):  
Jian Hua Bi ◽  
Yu Tao Zhao ◽  
Zhi Hong Jia ◽  
Song Li Zhang ◽  
Gang Chen
Keyword(s):  
Rare Earth ◽  
Radial Growth ◽  
Solidification Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rare Earth Addition ◽  
La Addition ◽  
Size And Morphology ◽  
Preparation Techniques

In-situ Al3Ti /A356 composites were synthesized by direct melt reaction method in Al-K2TiF6 system. The preparation techniques was discussed and the effects of Si, Mg, La (0.30%), Ce (0.30%) and multiple rare earth (0.15% La + 0.15%Ce) addition on microstructures of Al3Ti /A356 composites were investigated by X-ray diffraction and scanning electron microscope. The results show that the morphology and size of Al3Ti reinforcement are influenced significantly by Si, Mg and the optimal preparation process is composition with latter Si, Mg alloying. The Al3Ti precipitations during solidification process are restrained by 0.30% La addition or 0.30% Ce addition and lead in the uniform of Al3Ti size and morphology. The radial growth of Al3Ti is strongly restrained by rare earth composite addition, and the main morphology is slender-spherical like.

scholarly journals Surface and Optical Properties of Gd-Doped ZrO2 Nano Films

2020 ◽  
Vol 4 (1) ◽  
pp. 4
Author(s):  
Ognian Dimitrov ◽  
Irina Stambolova ◽  
Sasho Vassilev ◽  
Katerina Lazarova ◽  
Silvia Simeonova
Keyword(s):  
Thin Films ◽  
Rare Earth ◽  
Sol Gel ◽  
Earth Metal ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
Average Roughness ◽  
Force Microscopy ◽  
Atomic Force ◽  
Skin Conditions

Nanosized coatings of ZrO2 were deposited on silicon substrates using sol-gel and spin coating techniques. The precursor solutions were prepared from ZrOCl2.8H2O with the addition of different percentage (0.5–5%) of rare earth Gd3+ ions as dopant. The thin films were homogeneous, with average thickness of 115 nm and refractive index (n) of 1.83. The X-ray diffraction analysis (XRD) revealed the presence of a varying mixture of monoclinic and tetragonal ZrO2 polycrystalline phases, depending on the dopant, all of which with nanosized crystallites. Scanning electron microscopy (SEM) as well as atomic force microscopy (AFM) methods were deployed to investigate the surface morphology and roughness of the thin films, respectively. They revealed a smooth, well uniform and crack-free surface with average roughness of 0.8 nm. It was established that the dopant concentration affects the photoluminescence (PL) properties of the samples. The undoped films exhibited broad violet-blue PL emission, while the addition of Gd3+ ions resulted in new narrow bands in both UV-B and visible light regions, characteristic of the rare earth metal. The intensive emission located at 313 nm can find useful application in medical lamps for treatment of different skin conditions.

Preparation and Properties of Rare Earth-Doped TiO2 Thin Films by Sol-Gel Process

2014 ◽  
Vol 1033-1034 ◽  
pp. 1235-1238
Author(s):  
Tao Bai ◽  
Shi Gen Zhu
Keyword(s):  
Thin Films ◽  
Rare Earth ◽  
Sol Gel ◽  
Rare Earth Doping ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sol Gel Process ◽  
Scanning Electronmicroscopy ◽  
Rare Earth Doped ◽  
The Rare Earth

Rare earth doped titaniumdioxide (TiO2) thin films (rare earth-doped TiO2) have been successfully prepared on a glass substrate by a sol–gel route. After the rare earth-doped TiO2thin films were calcined at 773K for 1h, the effect of rare earth-doping on the properties were investigated using X-ray diffraction (XRD), scanning electronmicroscopy (SEM), ultraviolet–visible spectroscopy and thermogravimetric techniques (TG/DTG). The XRD results showed that rare earth-doped TiO2thin films contained only a single crystalline phase of anatase TiO2after calcining at 773K for 1h. SEM micrographs showed that rare earth-doped TiO2thin films have smooth surfaces containing granular nanocrystallines and are without cracks. The UV–vis absorption spectra showed that the absorption of the rare earth-doped TiO2thin films has a red-shift. From ambient to 1273K, it is about 12% of mass loss because of the volatilizing of water and organic and the phase transformation.

Effect of RE on Microstructure and Interfacial Reactions of SnAgCu Solder

2010 ◽  
Vol 154-155 ◽  
pp. 87-90 ◽  
Author(s):  
Yao Li Wang ◽  
Ke Ke Zhang ◽  
Guo Ji Zhao ◽  
Li Juan Han
Keyword(s):  
Rare Earth ◽  
Solder Alloy ◽  
Interfacial Reactions ◽  
X Ray Diffraction ◽  
Rare Earth Compound ◽  
Snagcu Solder ◽  
Rare Earth Addition ◽  
Resolution Electron ◽  
Rare Earth Content ◽  
Electronic Microscope

Effect of rare earth content on microstructure and interfacial reactions of low Ag content SnAgCu solder is researched by adopting the X-ray diffraction, JSM-5610LV scanning electronic microscope, energy spectrum analysis and JEM2100 ultrahigh resolution electron microscopy. The results show that proper quantities of rare earth (0.1%) can refine the eutectic microstructure of the solder alloy; and petal-like rare earth compound can be found in the solder alloy while the rare earth addition is 0.5%. The growing rate of the interfacial intermetallic compound can be reduced during the soldering with adding 0.1% rare earth in the Sn2.5Ag0.7Cu solder alloy.

scholarly journals FSM-16-SO3H nanoparticles as a novel heterogeneous catalyst: preparation, characterization, and catalytic application in the synthesis of polyhydroquinolines

2018 ◽  
Vol 41 (3-4) ◽  
pp. 91-101 ◽  
Author(s):  
Somayeh Hashemi-Uderji ◽  
Mohammad Abdollahi-Alibeik ◽  
Reza Ranjbar-Karimi
Keyword(s):  
Room Temperature ◽  
Ammonium Acetate ◽  
Sol Gel ◽  
Ethyl Cyanoacetate ◽  
Textural Properties ◽  
High Catalytic Activity ◽  
X Ray Diffraction ◽  
One Pot ◽  
X Ray ◽  
Catalytic Application

Abstract FSM-16-SO3H nanoparticles were prepared using a sol-gel method at room temperature. The prepared FSM-16-SO3H was used to catalyze the synthesis of polyhydroquinolines through a one-pot, four-component reaction of aldehydes, dimedone, ethyl cyanoacetate, and ammonium acetate under reflux condition in EtOH as a green solvent. To investigate the textural properties of the prepared catalyst, various techniques were applied such as X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, and Brunauer–Emmett–Teller. High catalytic activity, easy handling, and thermal stability are the superior properties that could be denoted after successive investigations of this catalyst. In addition, the catalyst can be recovered easily and reused effectively for several cycles.

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