Microwave-hydrothermal synthesis of gadolinium-doped nanocrystalline ceria in the presence of hexamethylenetetramine (original) (raw)
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Nanocrystalline ceria powders (CeO2) have been prepared by adding NaOH to a cerium ammonium nitrate aqueous solution under microwave–hydrothermal conditions. In particular the effect of the synthesis conditions (time, pressure and concentration of both the precursor and the precipitant agent solutions) on the physical properties of the crystals have been evaluated. Microwave–hydrothermal treatment of 5min at 13.4atm allows to obtain almost crystallized powders (amorphous phase 4%) as underlined by Rietveld-reference intensity ratio (RIR) results.
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Microwave induced combustion method was employed for the preparation of nickel mixed ceria nanocrystalline powder using cerium nitrate, nickel nitrate, glycine and sorbitol. Subsequently, three different molar composition of cerium nitrate was mixed with constant proportion of nickel nitrate, glycine and sorbitol to synthesis three samples. The resultant samples were analysed for structural, morphological and spectral characteristics using XRD, SEM, TEM, FTIR and UV'Vis spectroscopy. The crystallite sizes were about in the nano range of 27nm, 5nm & 4nm . There was a decrease in lattice parameter in the order of 5.4089A˚, 5.3921A˚ & 5.4014A˚. Degree of lattice distortion depends on NiO content in the ceria lattice. The FTIR spectrum shows the existence of groups such as -NO 2, -OH and C-H due to the solubility of nickel material. The absorption band is extended up to visible region in UV'Vis spectrum due to the substitution o f Ni ion. Keywords: Microwave, Optical properties,...
Iranian Journal of Science and Technology Transaction A-science, 2017
Recently, the GDC samples have been synthesized as promising materials for applying in solid oxide fuel cells. In the present research, two different kinds of gadolinium-doped ceria (GDC) nano-composites were prepared by a wetchemical method based on the sol-gel process and new precursors such as CeLH 2 , (pyda.H) 2 [(Ce(pydc) 3 ].2CH 3 OH and (pyda.H) 2 [(Gd(pydc) 3 ].2CH 3 OH, [pydc (2,6-Pyridinedicarboxylic acid), and GdLH 2 , pyda (2,6-diaminopyridine)]. The CeLH 2 and GdLH 2 coordination compounds have been prepared by high-energy ultrasound irradiation. The X-ray powder diffraction (XRD) results showed that the crystal lattice of the compounds (I), (II) was obtained cubic fluorite structures. The scanning electron microscope (SEM) analyses of the compounds (I), (II) indicated that the average grain sizes obtained about 20-30 and 50-70 nm, respectively. The results showed that using high intensity ultrasound can be utilized successfully for the synthesis of supramolecular coordination compounds. Keywords Nanoparticles Á Gadolinium-doped ceria Á Ce(III) complex Á Gd(II) complex Á Solid oxide fuel cell & M. Ranjbar
Journal of the European Ceramic Society, 2013
Gadolinium doped ceria (GDC) has received a lot of attention as possible electrolyte material for Intermediate-Temperature (500-800 • C) Solid Oxide Fuel Cells (IT-SOFC). Microwave heating has been recently considered in combination with precipitation for the production of oxide or non-oxide nano-powders. In this study, crystalline CeO 2 powders doped with different amount of gadolinium were successfully prepared by microwave-assisted polyol method under mild conditions and in one single step. The microwave heating was found to strongly influence the morphological properties of the powder especially for low gadolinium content. IR and thermal analyses helped to identify the major reaction path for the formation of the as-observed complex morphologies. Regardless to the morphology, the powders showed good densification behavior and expected electrochemical properties; Ce 0.9 Gd 0.1 O 1.95 exhibited the highest conductivity.
Doklady Chemistry, 2010
Nanocrystalline ceria (СеO 2 -δ ) and materials based thereon are widely used because of their unique physicochemical properties. Ceria is a component of protective coatings, three way catalysts, sensors, bio medical preparations, and so on. Special functional properties of nanocrystalline СеO 2 -δ are, first of all, caused by the dependence of its oxygen nonstoichi ometry on the particle size, which is most pronounced when the latter is reduced to 5-10 nm . It is worth noting that it is precisely the oxygen nonstoichiometry of СеO 2 -δ that is the key factor responsible for the bio logical activity of this material .
Microwave-assisted synthesis of ceria nanoparticles
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Cuprous oxide (Cu 2 O) nano-crystallites with different sizes were prepared via electrolysis method and characterized by X-ray powder diffraction (XRD) and transmission electron microscope (TEM). Its photo-catalytic activities in the degradation of methyl orange as the model pollutant using UV light as an energy source were investigated. The XRD patterns showed that the sizes of Cu 2 O nano-crystallite decreased with the increasement of cetyltrimethyl ammonium bromide (CTAB) being added into the electrolyte, which were ranging from 27 nm to 48 nm. The progress of photocatalytic degradation of the methyl orange was observed by monitoring the concentration change of the methyl orange solution. The highest decolorization ratio of 90% was observed for the sample prepared by addition of 0.05 g/L CTAB after photo-degradating 50 mg/L of methyl orange solution for 70 min. The mechanism of photo-degradation was discussed.
Influence of microwave heating on the growth of gadolinium-doped cerium oxide nanorods
Crystal Growth and …, 2008
In this communication, we demonstrate that the use of microwave heating during hydrothermal treatment drastically decreases the treatment time required to obtain gadolinium-doped ceria nanorods and that the oriented attachment is the dominant mechanism responsible for anisotropic growth. In fact, considering oriented attachment (OA) as a statistical mechanism, we postulate that the growth process conducted under microwave heating increases the effective collision rate. A plausible explanation for the increase of the effective collision rate under microwave irradiation is the increase in the collision cross-section of the particle.