scholarly journals Sol-gel synthesis and structure of La2O3-CoO-SiO2 powders

2008 ◽  
Vol 2 (2) ◽  
pp. 103-108 ◽  
Author(s):  
Lachezar Radev ◽  
Liliana Pavlova ◽  
Bisserka Samuneva ◽  
Elena Kashchieva ◽  
Irena Mihailova ◽  
...  
Keyword(s):  
Chelating Agents ◽  
Catalytic Properties ◽  
Sol Gel ◽  
Treatment Temperature ◽  
Solution Crystallization ◽  
Metal Nitrates ◽  
Crystallite Sizes ◽  
Solgel Method ◽  
Sol Gel Synthesis ◽  
Reaction In Solution

LaCoO3 powders are studied because they exhibit interesting electrical, magnetic and catalytic properties. In this paper, new synthesized La2O3-CoO-SiO2 powders with different quantity of silica were prepared via solgel method in aqua media, starting from metal nitrates with different chelating agents. The relation between the reaction in solution, crystallization pathway and morphology were discussed. In LaCoO3-SiO2 powders, depending on the content of SiO2 and the treatment temperature (700-1100?C), different crystalline phases (LaCoO3, Co2 SiO4 and La9.31 (SiO4 )6 O2) were observed with the crystallite sizes ranging from 50 to 100 nm. It was proved that chemical composition and nature of used additives has influence on the phase formation and structure of obtained nanomaterials.

Sol-gel Synthesis, Magnetic and Structural Characterization of BaFe11.6–2xMxTixO19 (M=Co, Zn, Sn) Compounds.

2002 ◽  
Vol 755 ◽  
Author(s):  
G. Mendoza-Suárez ◽  
A.F. Fuentes ◽  
J.I. Escalante-García ◽  
O.E. Ayala-Valenzuela
Keyword(s):  
Magnetocrystalline Anisotropy ◽  
Sol Gel ◽  
Treatment Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Barium Ferrites ◽  
Crystallite Sizes ◽  
Sol Gel Synthesis

ABSTRACTSubstituted barium ferrites powders with Ti4+-M2+ (M = Co, Zn, Sn) cationic mixtures were prepared by a sol-gel route. The materials were heat-treated in the range 925–1000 °C and characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The results showed that the effect of the substitution, x was to lower the coercivity (Hc), owing to the decrease of the magnetocrystalline anisotropy of the magnetoplumbite structure of the BaM. In this regard Sn-Ti substitutions tended to decrease Hc more rapidly than Zn-Ti and Ti-Co substitutions, in that order. Regarding the saturation magnetization (Ms), Zn-Ti mixtures showed slightly better Ms than Ti-Co substitutions; however, the Sn-Ti showed a more marked decrease as x increased. As revealed by SEM, the effect of the heat-treatment temperature was to increase the volume of multi-domain particles, following a Hc decrease due to grain coarsening. Contrarily, as a result of the improved crystallinity of the samples, as observed from the XRD peaks, Ms enhancement was recorded. Crystallite sizes decreased below 100 nm as x increased, although it was also dependent on the cationic mixture. In this respect Sn-Ti substitutions needed higher treatment temperatures to yield materials with adequate crystallinity and phase constitution.

Effects of chelating agents on the sol-gel synthesis of nano-zirconia: Comparison of the Pechini and sugar-based methods

2020 ◽  
Vol 27 (5) ◽  
pp. 693-702 ◽  
Author(s):  
Faramarz Kazemi ◽  
Farzin Arianpour ◽  
Mahdiar Taheri ◽  
Ali Saberi ◽  
Hamid Reza Rezaie
Keyword(s):  
Chelating Agents ◽  
Sol Gel ◽  
Sol Gel Synthesis

Optimization of Experimental Parameters to the Formation of Bi2212 Phase via Sol-Gel Method

2011 ◽  
Vol 328-330 ◽  
pp. 1499-1502
Author(s):  
Hua Zhe Yang ◽  
Ye Song He ◽  
Yang Ji ◽  
Zi Mu Li ◽  
Hao Zhu
Keyword(s):  
Sol Gel ◽  
Precursor Solution ◽  
Chelating Agent ◽  
Solution Concentration ◽  
Treatment Temperature ◽  
Gel Method ◽  
Sol Gel Method ◽  
Metal Nitrates ◽  
Water As Solvent ◽  
Experimental Parameters

Bi-2212 superconducting phase was synthesized via sol-gel method, and the experimental parameters such as the concentration of precursor solution and heat treatment temperature were adjusted to find the optimal conditions. Metal nitrates were adopted as the starting materials and ethylenediaminetetracetic acid (EDTA) as chelating agent. Precursor solutions and gel with different concentration were obtained through the addition of different content of distilled water as solvent followed by heating at certain temperature to form grey powders. Afterwards, the powders were sintered at different temperature for 10 hours, respectively. X-ray diffraction (XRD) was adopted to investigate the phase purity and crystallinity of the sample derived. Results reveal that the optimized precursor solution concentration is 27% and the optimized sintering temperature is 850°C.

scholarly journals Sol-Gel Synthesis and Characterization of Cubic Bismuth Zinc Niobium Oxide Nanopowders

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Ganchimeg Perenlei ◽  
Peter C. Talbot ◽  
Wayde N. Martens
Keyword(s):  
Niobium Oxide ◽  
Sol Gel ◽  
Atomic Ratio ◽  
X Ray Diffraction ◽  
Metal Acetate ◽  
Chemical Homogeneity ◽  
Liquid Suspension ◽  
Crystallite Sizes ◽  
Sol Gel Synthesis

Bismuth zinc niobium oxide (BZN) was successfully synthesized by a diol-based sol-gel reaction utilizing metal acetate and alkoxide precursors. Thermal analysis of a liquid suspension of precursors suggests that the majority of organic precursors decompose at temperatures up to 150°C, and organic free powders form above 350°C. The experimental results indicate that a homogeneous gel is obtained at about 200°C and then converts to a mixture of intermediate oxides at 350–400°C. Finally, single-phased BZN powders are obtained between 500 and 900°C. The degree of chemical homogeneity as determined by X-ray diffraction and EDS mapping is consistent throughout the samples. Elemental analysis indicates that the atomic ratio of metals closely matches a Bi1.5ZnNb1.5O7composition. Crystallite sizes of the BZN powders calculated from the Scherrer equation are about 33–98 nm for the samples prepared at 500–700°C, respectively. The particle and crystallite sizes increase with increased sintering temperature. The estimated band gap of the BZN nanopowders from optical analysis is about 2.60–2.75 eV at 500-600°C. The observed phase formations and measured results in this study were compared with those of previous reports.

Sol-Gel Synthesis and Characterization of BaAl2O4 and Co: BaAl2O4 Nanoparticles

2010 ◽  
Vol 148-149 ◽  
pp. 1067-1070 ◽  
Author(s):  
Cai Na Luan ◽  
Jin Ma ◽  
Zhen Zhu ◽  
Ling Yi Kong ◽  
Qiao Qun Yu
Keyword(s):  
Sol Gel ◽  
Visible Region ◽  
Emission Spectra ◽  
Chelating Agent ◽  
Nano Particles ◽  
Luminescence Spectroscopy ◽  
Metal Nitrates ◽  
Heat Treated ◽  
Nano Crystal ◽  
Sol Gel Synthesis

In this paper, we prepared BaAl2O4 and Co:BaAl2O4 nanoparticles from aqueous solution of metal nitrates containing citric acid as a chelating agent by sol-gel method. The gel was heat-treated at temperatures ranging from 710°C to 1000°C. The heat-treated powders were characterized by X-ray diffraction analysis (XRD), infrared spectra (IR) and luminescence spectroscopy. From the results of the characterization, we find the prepared powders are pure nano-particles of BaAl2O4 after heat-treated at 900°C temperature. The emission spectra of Co: BaAl2O4 in the visible region indicates the existence of Co2+ in the tetrahedral sites of BaAl2O4 nano-crystal.

Non-aqueous sol–gel synthesis, characterization and catalytic properties of metal fluoride supported palladium nanoparticles

2008 ◽  
Vol 78 (1-2) ◽  
pp. 80-91 ◽  
Author(s):  
Pratap T. Patil ◽  
Anton Dimitrov ◽  
Holm Kirmse ◽  
Wolfgang Neumann ◽  
Erhard Kemnitz
Keyword(s):  
Palladium Nanoparticles ◽  
Catalytic Properties ◽  
Sol Gel ◽  
Metal Fluoride ◽  
Supported Palladium ◽  
Sol Gel Synthesis

scholarly journals SOL-GEL SYNTHESIS AND CATALYTIC PROPERTIES OF VANADIUM PHOSPHATES BULK MATERIALS

2000 ◽  
Vol 11 (0) ◽  
pp. 87-93 ◽  
Author(s):  
S. A. Ennaciri ◽  
K. Malka ◽  
C. Louis ◽  
P. Barboux ◽  
C. R'kha ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Sol Gel ◽  
Bulk Materials ◽  
Vanadium Phosphates ◽  
Sol Gel Synthesis
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