scholarly journals Influence of mg doping on structural, optical and photocatalytic performances of ceria nanopowders

2017 ◽  
Vol 11 (4) ◽  
pp. 304-310
Author(s):  
Branko Matovic ◽  
Jelena Lukovic ◽  
Bojan Stojadinovic ◽  
Sonja Askrabic ◽  
Aleksandra Zarubica ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Oxygen Vacancies ◽  
Uv Light ◽  
Doped Ceria ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceria Solid Solutions ◽  
Fluorite Type ◽  
Photocatalytic Performances ◽  
Mg Doped

Nanosized Mg-doped ceria powders were obtained by self-propagating room temperature reaction without using surfactants or templates. X-ray diffraction analysis and field emission scanning microscopy results showed that the doped samples are solid solutions with fluorite-type structure and spherical morphology. Raman spectra revealed an increase in the amount of oxygen vacancies with the increase of Mg concentration. This increasing results in a narrowing of the bandgap of CeO2. The photocatalytic performances of the Mg-doped ceria solid solutions were evaluated by decomposing an organic dye, crystal violet under UV irradiation. The Mg-doped ceria solid solutions exhibit significantly better photocatalytic activity than the pure CeO2 and commercial TiO2. The higher first rate constant of the Mg-doped samples demonstrated that they are much more efficient than TiO2 and CeO2 under UV light. Mg2+ dopant ions and oxygen vacancies play a significant role in the enhancement of photocatalytic performances of the Mg-doped ceria.

scholarly journals Oxide ionic conductivity and microstructures of Pr and Sm co-doped CeO2-based systems

2018 ◽  
Vol 16 (1) ◽  
pp. 827-832 ◽  
Author(s):  
Aliye Arabacı
Keyword(s):  
Ionic Conductivity ◽  
Sem Analysis ◽  
Doped Ceria ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fluorite Type ◽  
Doped Ceo2 ◽  
Oxide Ionic Conductivity ◽  
Total Ionic Conductivity ◽  
Co Doped

AbstractThe compositions Ce0.80Sm0.2-xPrxO2-δ (x=0-0.12) were prepared through the citrate-nitrate method. The synthesized Pr3+ and Sm3+ co-doped ceria powders with different compositions were calcined at 600°C for 3 h. Phase structure of the calcined powders was characterized by X-Ray diffraction (XRD) analysis.All the calcined samples were found to be ceria based solid solutions of fluorite type structures. The morphology examinations were carried out by scanning electron microscopy (SEM) analysis. Relative density of more than 91% of the theoretical can be achieved by sintering the Ce0.80Sm0.2-xPrxO2-δ pellets at 1400°C for 6 h. The two-probe a.c. impedance spectroscopy was used to study the ionic conductivity of the doped ceria samples. The Ce0.80Sm0.80Pr0.12O1.90 composition showed the highest total ionic conductivity value which is 2.39 × 10−2 S/cm at 600°C.

Low-temperature preparation and structural characterization of Pr-doped ceria solid solutions

2002 ◽  
Vol 17 (4) ◽  
pp. 797-804 ◽  
Author(s):  
E. López-Navarrete ◽  
A. Caballero ◽  
A. R. González-Elipe ◽  
M. Ocaña
Keyword(s):  
Solid Solutions ◽  
Photoelectron Spectroscopy ◽  
Heating Temperature ◽  
Doped Ceria ◽  
X Ray ◽  
Ceria Solid Solutions ◽  
Low Temperature Preparation ◽  
Distribution Composition ◽  
X Ray Absorption

We report a method for preparing Pr-doped ceria by pyrolysis at 600 °C of aerosols consisting of aqueous solutions of Ce(III) nitrate and Pr(III) chloride. This procedure involves an important decrease of the temperature of solid solution formation (several hundred degrees) when compared with the ceramic and other previously reported methods, and does not require the addition of fluxes. The prepared samples and their products after thermal treatment were characterized in terms of particle shape and size distribution, composition, and crystalline structure. The color properties of these solid solutions were also evaluated as a function of the heating temperature and composition; the optimum red pigment was obtained for samples with a Pr/Ce mole ratio = 0.063 heated for 3 h at 600 °C. The oxidation state of the Pr cations and their distribution in the CeO2 matrix were investigated by x-ray absorption near-edge spectroscopy and x-ray photoelectron spectroscopy. A mixture of trivalent and tetravalent Pr was detected in all studies samples. The Pr(IV)/Pr(III) ratio increased as the Pr content or the heating temperature increased. These Pr(III) cations were found to be mainly located in the particles' outer layers, in which an enrichment of Pr was detected for all samples heated at 600 °C. The further calcination of the pigments at 1200 °C gave rise to a certain diffusion of the Pr cations toward the particle core, which was more significant for the sample with the highest Pr content (Pr/Ce mole ratio 4 0.091).

Synthesis of Gadolinium Doped Ceria Ceramic Powder by Polymeric Precursor Method (Pechini)

2014 ◽  
Vol 798-799 ◽  
pp. 182-188 ◽  
Author(s):  
Jesús Mauricio González Martínez ◽  
Rodrigo Arabey Muñoz Meneses ◽  
Cosme Roberto Moreira da Silva
Keyword(s):  
Ceramic Powder ◽  
Doped Ceria ◽  
Polymeric Precursor ◽  
X Ray Diffraction ◽  
Precursor Method ◽  
Calcination Process ◽  
X Ray ◽  
Before And After ◽  
Fluorite Type ◽  
Gadolinium Doped Ceria

The synthesis by polymeric precursors method (Pechini) was used to acquire gadolinium doped ceria forming Ce0,8Gd0,2O1,9 system, reaching high stoichiometric control features and nanosized particles to form dense solid electrolyte of high ionic conductivity. The synthesis was performed with cerium and gadolinium nitrates hexahydrates, citric acid and ethylene glycol. After the pre-calcination at 250°C/18h a resin was obtained like an expanded foam (puff). According to the iterature, this fact indicates that there is a reduction of agglomerates amount in a ceramic powder. A thermogravimetry-differential thermal analysis evaluated the thermal behavior of the resin. Infrared spectroscopy determined the organic matter and nitrates presence, before and after the calcination process. The X-ray diffraction identified the fluorite-type structure and was determined the crystallite size by the Scherrer equation in 22 and 46 nm for the powder calcined respectively at 600 and 800°C. The scanning electron microscopy evaluated the agglomeration degree and the morphology of the powders.

scholarly journals Crystal structure analysis of Nd-doped ceria solid solutions

2008 ◽  
Vol 40 (1) ◽  
pp. 63-68 ◽  
Author(s):  
B. Matovic ◽  
J. Dukic ◽  
A. Devecerski ◽  
S. Boskovic ◽  
M. Ninic ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid Solutions ◽  
Structural Information ◽  
Crystal Structure Analysis ◽  
Ion Concentration ◽  
Doped Ceria ◽  
Cell Parameters ◽  
Ceria Solid Solutions ◽  
Fluorite Type ◽  
Powder Particles

This paper deals with Nd-doped ceria solid solutions: Ce1-xNdxO2-d with "x" ranging from 0 to 0.25. Six different powders were synthesized by applying the method based on selfpropagating room temperature reaction (SPRT) between metallic nitrates and sodium hydroxide. The method is known to assure very precise stoichiometry of the final product in comparison with a tailored composition. Rietveld refinement was employed to get structural information on the synthesized powder. An increase of Nd ion concentration increases the unit cell parameters and average bond distances. We have shown that all obtained powders were solid solutions with a fluorite-type crystal structure and all powder particles were of nanometric size (about 3 nm).

scholarly journals The interaction between cerium dioxide, lanthanum and europium oxides at 1500°C

2021 ◽  
Vol 15 (1) ◽  
pp. 32-39
Author(s):  
Olena Andrievskaya ◽  
Oksana Kornienko ◽  
Oleksandr Bykov ◽  
Olga Chudinovich ◽  
Larysa Spasonova
Keyword(s):  
Solid Solutions ◽  
Cerium Dioxide ◽  
Phase Relationship ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Wide Range ◽  
Phase Fields ◽  
Unit Cells ◽  
Fluorite Type

Materials based on CeO2-La2O3-Eu2O3 and La2O3-Eu2O3 systems are promising candidates for a wide range of applications, but the phase relationship has not been studied systematically previously. The phase relations in the CeO2-La2O3-Eu2O3 ternary system at 1500?C and binary La2O3-Eu2O3 system at 1600-1500?C were studied in air by X-ray diffraction (XRD) investigation in the overall concentration range. The isothermal section of the phase diagram for the CeO2-La2O3-Eu2O3 system has been constructed. It was established that in the ternary CeO2-La2O3-Eu2O3 system there exist fields of solid solutions based on hexagonal (A) modification of La2O3, cubic modification of CeO2 with fluorite-type structure (F), cubic (C) and monoclinic (B) modification Eu2O3. It was established that in the binary La2O3-Eu2O3 system there exist fields of solid solutions based on hexagonal (A) modification of La2O3 and monoclinic (B) modification Eu2O3. The phases were separated by two-phase fields (A+B). The refined lattice parameters of the unit cells for solid solutions and microstructures of the definite field of compositions for the systems were determined.

scholarly journals Enhanced Ultraviolet Photodetector Based on Mg-Doped ZnO Nanorods Films

2019 ◽  
Vol 29 (3) ◽  
pp. 158 ◽  
Author(s):  
Hussein Abdullah Hameed
Keyword(s):  
Uv Light ◽  
Zno Nanorods ◽  
Optical Absorption Spectroscopy ◽  
Near Band Edge ◽  
X Ray Diffraction ◽  
X Ray ◽  
Glass Substrates ◽  
Metal Semiconductor Metal ◽  
Doped Zno ◽  
Mg Doped

Magnesium-doped zinc oxide (ZnO: Mg) nanorods and nanotubes films were prepared by hydrothermal method deposited on glass substrates. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), photoluminescence (PL), and optical absorption spectroscopy (UV) were performed to characterize the prepared films. X-ray diffraction analysis showed a decrease in the lattice parameters of Mg doped ZnO NRs. The Photoluminescence of the undoped and Mg-doped ZnO NRs displayed a near band edge. At 10 V bias, the metal-semiconductor-metal (MSM) ultraviolet (UV) photodetector performance of the Mg-doped ZnO prepared for various Mg concentrations of 0.0, 0.02, and 0.06 was investigated under radiation of 40μW/cm2 at the wavelengths of 365 and 385 nm UV light. The responsivity, detectivity and quantum efficiency of Mg-doped based on MSM detector were 0.118A/W, 1.0579*1012 and 40.05157 under UV of wavelength 365nm respectively.

Lattice Parameters of Gd-Doped Ceria Electrolytes

2005 ◽  
Vol 494 ◽  
pp. 175-180 ◽  
Author(s):  
B. Matović ◽  
Snezana Bošković ◽  
Ljiljana Živković ◽  
M.D. Vlajić ◽  
Vladimir D. Krstić
Keyword(s):  
Solid Solutions ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
Doped Ceria ◽  
Ceria Solid Solutions ◽  
Fluorite Type ◽  
Parameter Versus ◽  
Average Size ◽  
20 Nm ◽  
Type Crystal

This paper deals with Gd-doped ceria solid solutions: Ce1−XGdXO2−d with "x" ranging from 0 to 0.2. Four different powders were synthesized by modified glycine nitrate procedure with very precise stoichiometry according to tailored composition. The method was modified by decreasing glycine/nitrate ratio to 0.5. All obtained solid solutions exhibit a fluorite-type crystal structure with composition dependent lattice parameters. The variation of the lattice parameter was studied and correlated with the equation describing the ion-packing model. It has been found that the change of lattice parameter versus Gd concentration obeys Vegard's rule very well. Results also show that all powders are nanometric in size. The average size of Ce1−XGdXO2−d particles is about 20 nm.

scholarly journals Crystal structure analysis of Nd-doped ceria solid solutions

2008 ◽  
Vol 40 (1) ◽  
pp. 63-68
Author(s):  
B. Matovic ◽  
J. Dukic ◽  
A. Devecerski ◽  
S. Boskovic ◽  
M. Ninic ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid Solutions ◽  
Structural Information ◽  
Crystal Structure Analysis ◽  
Ion Concentration ◽  
Doped Ceria ◽  
Cell Parameters ◽  
Ceria Solid Solutions ◽  
Fluorite Type ◽  
Powder Particles

This paper deals with Nd-doped ceria solid solutions: Ce1-xNdxO2-d with "x" ranging from 0 to 0.25. Six different powders were synthesized by applying the method based on selfpropagating room temperature reaction (SPRT) between metallic nitrates and sodium hydroxide. The method is known to assure very precise stoichiometry of the final product in comparison with a tailored composition. Rietveld refinement was employed to get structural information on the synthesized powder. An increase of Nd ion concentration increases the unit cell parameters and average bond distances. We have shown that all obtained powders were solid solutions with a fluorite-type crystal structure and all powder particles were of nanometric size (about 3 nm).

Ionic Conductivity of Gd- and Y-Doped Ceria-Zirconia Solid Solutions

2006 ◽  
Vol 61 (7) ◽  
pp. 916-922 ◽  
Author(s):  
Vera Rührup ◽  
Hans-Dieter Wiemhöfer
Keyword(s):  
Ionic Conductivity ◽  
Solid Solutions ◽  
Oxygen Vacancies ◽  
Fluorite Structure ◽  
Lattice Parameter ◽  
Total Conductivity ◽  
Doped Ceria ◽  
Deep Minimum ◽  
X Ray ◽  
Zirconia Content

The total conductivity of the solid solutions (Ce1−xZrx)0.8Gd0.2O1.9 and (Ce1−xZrx)0.8Y0.2O1.9 was measured in air as a function of temperature (T = 300 °C- 600 °C) and composition (x = 0.0 - 0.9). A deep minimum of the bulk ionic conductivity was found for equal fractions of ceria and zirconia. It indicates enhanced defect association and ordering of the oxygen vacancies around x = 0.5. X-ray analysis (Guinier technique) showed the diffraction pattern of the cubic fluorite structure for all investigated compositions 0 < x < 1. The lattice parameter decreased linearly with increasing zirconia content x.

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