scholarly journals Electrical and thermal properties of 10 mol% Gd3+ doped ceria electrolytes synthesized through citrate combustion technique

2009 ◽  
Vol 3 (3) ◽  
pp. 137-143 ◽  
Author(s):  
Viswanathan Mangalaraja ◽  
Solaiappan Ananthakumar ◽  
Manidurai Paulraj ◽  
Kasimayan Uma ◽  
Marta López ◽  
...  
Keyword(s):  
Citric Acid ◽  
Room Temperature ◽  
Doped Ceria ◽  
Nanocrystalline Ceria ◽  
Structure Surface ◽  
Particle Size And Morphology ◽  
Powder Properties ◽  
Size And Morphology ◽  
Combustion Technique ◽  
Ceria Electrolyte

Nanocrystalline ceria electrolyte doped with 10 mol% gadolinia [Ce0.9Gd0.1O1.95] was synthesized by citric acid combustion technique involving mixtures of cerium nitrate oxidizer (O) and citric acid fuel (F) taken in the ratio of O/F=1. The as combusted precursors produced crystalline ceria particles upon calcination performed at 700?C for 2h. Ceria pellets were made and sintered at temperatures 1200, 1400 and 1500?C with a dwell time of 2, 4 and 6 h. The sintered microstructures, electrical and thermal conductivities and thermal diffusivity properties were evaluated in addition to the powder properties such as crystalline structure, surface area, particle size and morphology. Sintered ceria samples had 99% theoretical density at 1500?C/6h. The sintered microstructures exhibit dense ceria grains with sizes 500 nm to one micron. The electrical conductivity versus temperature showed conductivity in the order of 10-2 and 10-1 S?cm-1 at 500 and 700?C, respectively. The ceria sintered at 1500?C has the maximum thermal conductivity of ~2.79 W?m-1K-1 at room temperature. .

Preparation of High-Purity Ultrafine α-Al2O3 by Solid-State Reaction at Room Temperature

2008 ◽  
Vol 368-372 ◽  
pp. 683-685
Author(s):  
Cheng Wei Hao ◽  
Bo Lin Wu ◽  
Ji Yan Li
Keyword(s):  
Solid State ◽  
High Purity ◽  
Solid State Reaction ◽  
Room Temperature ◽  
Raw Materials ◽  
Phase Particle ◽  
Phase Transformation Temperature ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Α Al2o3

Ammonium aluminium carbonate hydroxide (AACH), with a small quantity of γ-AlOOH, was synthesized through solid-state reaction at room temperature using AlCl3·6H2O and NH4HCO3 as raw materials and polyethylene glycol (PEG-10000) as the dispersant. After calcined at 1100°C for 1.5h, α-Al2O3 powders with primary particle sizes of 20~30nm were obtained. The crystal phase, particle size and morphology of the high-purity ultrafine α-Al2O3 were characterized. The results showed that a small quantity of γ-AlOOH in the AACH decomposed and formed crystal seeds. The presence of crystal seeds reduced the nucleation activation energy and therefore reduced the phase transformation temperature.

Solvothermal Synthesis and Characterization of Lithium Tantalate Nanoparticles

2014 ◽  
Vol 602-603 ◽  
pp. 19-22 ◽  
Author(s):  
Lin Qiang Gao ◽  
Hai Yan Chen ◽  
Zhen Wang ◽  
Xin Zou
Keyword(s):  
Electron Microscopy ◽  
Solvothermal Synthesis ◽  
Room Temperature ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Particle Size And Morphology ◽  
Size And Morphology

Nanoscale LiTaO3 powders with perovskite structure were synthesized using the solvothermal technique with glycol as solvent at 240°C for 12h. The powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). XRD was used to elucidate room temperature structures using Rietveld refinement. The powders were pure single pervoskite phase with high crystallinity. FESEM and TEM were used to determine particle size and morphology. The average LiTaO3 grain size was estimated to be < 200nm, and TEM images indicated that LiTaO3 particles had a brick-like morphology. In addition, the effect of the temperature on the LiTaO3 power characterisitics was also detailed studied.

scholarly journals Synthesis and characterization of (Ba, Yb) doped ceria nanopowders

2011 ◽  
Vol 5 (2) ◽  
pp. 69-72 ◽  
Author(s):  
Branko Matovic ◽  
Jelena Pantic ◽  
Jelena Lukovic ◽  
Svetlana Ilic ◽  
Nadezda Stankovic ◽  
...  
Keyword(s):  
Room Temperature ◽  
Average Diameter ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Doped Ceria ◽  
Fixed Amount ◽  
Fluorite Type ◽  
Powder Properties ◽  
The Mean

Nanometric size (Ba, Yb) doped ceria powders with fluorite-type structure were obtained by applying selfpropagating room temperature methods. Tailored composition was: Ce0.95-xBa0.05YbxO2-? with fixed amount of Ba - 0.05 and varying Yb content 'x' from 0.05 to 0.2. Powder properties such as crystallite and particle size and lattice parameters have been studied. R?ntgen diffraction analyses (XRD) were used to characterize the samples at room temperature. Also, high temperature treatment (up to 1550?C) was used to follow stability of solid solutions. The mean diameters of the nanocrystals are determined from the full width at half maxima (FWHM) of the XRD peaks. It was found that average diameter of crystallites is less than 3 nm. Williamson- Hall plots were used to separate the effect of the size and strain in the nanocrystals.

Nanocrystalline Ceria Powders Through Citrate–Nitrate Combustion

2006 ◽  
Vol 6 (1) ◽  
pp. 209-214 ◽  
Author(s):  
R. D. Purohit ◽  
S. Saha ◽  
A. K. Tyagi
Keyword(s):  
Citric Acid ◽  
Primary Particle ◽  
Flame Temperature ◽  
Cerium Nitrate ◽  
Molar Ratios ◽  
Auto Ignition ◽  
Nanocrystalline Ceria ◽  
Powder Characteristics ◽  
Cold Pressed ◽  
Combustion Technique

Nanocrystalline ceria powders have been synthesized by combustion technique using citric acid as a fuel and nitrate as an oxidizer. The auto-ignition of the gels containing cerium nitrate and citric acid resulted in ceria powders. A theory based on adiabatic flame temperature for different citric acid-to-cerium nitrate molar ratios has been proposed to explain the nature of combustion reaction and its correlation with the powder characteristics. Specific surface area and primary particle size of the ceria powder obtained through fuel-deficient precursor was found to be ≈127 m2/g and 2.5–10 nm, respectively. The combustion synthesized ceria powder when cold pressed and sintered in air at 1250 °C for 1 hour resulted in ≈96% of its theoretical density with sub-micron grains.

Nanocrystalline Doped Ceria-Zirconia Fluorite-Like Solid Solutions Promoted by Pt: Structure, Surface Properties and Catalytic Performance in Syngas Generation

2006 ◽  
Vol 988 ◽  
Author(s):  
Vladislav A Sadykov ◽  
Natalia Mezentseva ◽  
Galina Alikina ◽  
Anton Lukashevich ◽  
Vitalii Muzykantov ◽  
...  
Keyword(s):  
Isotope Exchange ◽  
Surface Composition ◽  
Catalytic Performance ◽  
Autothermal Reforming ◽  
Doped Ceria ◽  
Oxygen Mobility ◽  
Physical Methods ◽  
Oxygen Isotope Exchange ◽  
Nanocrystalline Ceria ◽  
Structure Surface

AbstractNanocrystalline ceria-zirconia samples doped with rare-earth (Gd, Pr, Sm, La) cations were prepared via modified Pechini route. Effect of their real structure and surface composition characterized by a combination of sophisticated physical methods (XRD, TEM +EDX, EXAFS, WAXS, UV-Vis, XPS, SIMS) on the mobility and reactivity of the lattice oxygen estimated by oxygen isotope exchange, H2, CH4 and CO TPR was analyzed. For the reaction of acetone autothermal reforming into syngas, catalytic activity correlates rather well with the oxygen mobility controlled by the type and content of a dopant

Direct manipulation of particle size and morphology of ordered mesoporous silica by flow synthesis

RSC Advances ◽  
2015 ◽  
Vol 5 (18) ◽  
pp. 13331-13340 ◽  
Author(s):  
T. N. Ng ◽  
X. Q. Chen ◽  
K. L. Yeung
Keyword(s):  
Particle Size ◽  
Mesoporous Silica ◽  
Hollow Spheres ◽  
Ordered Mesoporous Silica ◽  
Direct Manipulation ◽  
Flow Synthesis ◽  
Precise Control ◽  
Ordered Mesoporous ◽  
Particle Size And Morphology ◽  
Size And Morphology

Flow-synthesis of mesoporous silica allows deliberate and precise control over the size and shapes and enables the preparation of complex microstructures (i.e., hollow spheres).

scholarly journals Synthesis and Characterization of a Fe3O4@PNIPAM-Chitosan Nanocomposite and Its Potential Application in Vincristine Delivery

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1704
Author(s):  
Cynthia N. Hernández-Téllez ◽  
Ana G. Luque-Alcaraz ◽  
Maribel Plascencia-Jatomea ◽  
Hiram J. Higuera-Valenzuela ◽  
Mabeth Burgos-Hernández ◽  
...  
Keyword(s):  
Fe3o4 Nanoparticles ◽  
Release Kinetics ◽  
Magnetic Core ◽  
Systematic Evaluation ◽  
Solution Temperature ◽  
Core Shell ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Thermomagnetic Properties ◽  
Release Model

In this research, we conducted a systematic evaluation of the synthesis parameters of a multi-responsive core-shell nanocomposite (Fe3O4 nanoparticles coated by poly(N-isopropylacrylamide) (PNIPAM) in the presence of chitosan (CS) (Fe3O4@PNIPAM-CS). Scanning electron microscopy (SEM) was used to follow the size and morphology of the nanocomposite. The functionalization and the coating of Fe3O4 nanoparticles (Nps) were evaluated by the ζ-potential evolution and Fourier Transform infrared spectroscopy (FTIR). The nanocomposite exhibited a collapsed structure when the temperature was driven above the lower critical solution temperature (LCST), determined by dynamic light scattering (DLS). The LCST was successfully shifted from 33 to 39 °C, which opens the possibility of using it in physiological systems. A magnetometry test was performed to confirm the superparamagnetic behavior at room temperature. The obtained systems allow the possibility to control specific properties, such as particle size and morphology. Finally, we performed vincristine sulfate loading and release tests. Mathematical analysis reveals a two-stage structural-relaxation release model beyond the LCST. In contrast, a temperature of 25 °C promotes the diffusional release model. As a result, a more in-depth comprehension of the release kinetics was achieved. The synthesis and study of a magnetic core-shell nanoplatform offer a smart material as an alternative targeted release therapy due to its thermomagnetic properties.

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