Syntheses and Characterisation of Gd3Al5O12 and La3Al5O12 Garnets

2007 ◽  
Vol 72 (3) ◽  
pp. 321-333 ◽  
Author(s):  
Edita Garskaite ◽  
Natalija Dubnikova ◽  
Arturas Katelnikovas ◽  
Jiří Pinkas ◽  
Aivaras Kareiva
Keyword(s):  
Phase Composition ◽  
Ir Spectroscopy ◽  
Metal Ions ◽  
Sol Gel ◽  
Aqueous Media ◽  
Experimental Conditions ◽  
Lanthanide Ion ◽  
In Situ Generation ◽  
Xrd Patterns

A sol-gel method based on in situ generation of mixed-metal chelates by complexing metal ions with ethane-1,2-diol in aqueous media has been elaborated to prepare lanthanide-ion containing garnets, Gd3Al5O12 (GAG) and La3Al5O12 (LAG). XRD patterns of the powders sintered at 1 000 °C revealed the formation of monophasic GAG. However, LAG does not form under the same experimental conditions. The phase composition of the samples was characterised by IR spectroscopy. Microstructural features of the polycrystalline garnets were studied by SEM.

Synthesis, Characterization and Properties of PANI/(La-Nd Doped BaFe12O19) Composites

2017 ◽  
Vol 727 ◽  
pp. 327-334
Author(s):  
Yan Wang ◽  
Jun Wang ◽  
Xiao Fei Zhang ◽  
Ya Qing Liu
Keyword(s):  
Sol Gel ◽  
Network Analyzer ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Structure Morphology ◽  
Xrd Patterns ◽  
Hexagonal Platelet ◽  
Peak Value ◽  
Properties Of Composites

La-Nd co-doped barium hexaferrites, Ba0.7(LamNdn)0.3Fe12O19 (D-BaM), were successfully prepared by sol-gel method. PANI / D-BaM composites were synthesized by in-situ polymerization in solution. The structure, morphology and properties of samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), four-probe conductivity tester and vector network analyzer. The XRD patterns showed that the crystal structure of all the samples exist as M-type phases. The SEM images revealed that the particles presented a hexagonal platelet-like morphology. The magnetic properties could be improved by substitutions of La and Nd ions. The saturation magnetization (Ms) and coercive force (Hc) increased with the change of La / Nd ratio to the maximum at La / Nd = 3:1. The doped particles have also been embedded in conductive PANI to prepare electromagnetic materials, and the conductivity kept on the order of 10-2. The microwave absorbing properties of composites at 30 MHz-6 GHz improved obviously, the peak value of reflection loss could reach-7.5 dB.

A Copper Halide Promoted Regioselective Halogenation of Coumarins Using N-Halosuccinimide as Halide Source

Synlett ◽  
2019 ◽  
Vol 30 (05) ◽  
pp. 630-634 ◽  
Author(s):  
Min Zhang ◽  
Jinling Su ◽  
Yan Zhang ◽  
Mingren Chen ◽  
Weiming Li ◽  
...  
Keyword(s):  
Metal Halide ◽  
Regioselective Synthesis ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Copper Halide ◽  
Experimental Conditions ◽  
Heteroaromatic Compounds ◽  
Convenient Approach ◽  
In Situ Generation

A safe, convenient, and regioselective synthesis of 3-halo coumarins using a metal halide (CuX2 alone or with ZnX2) promoted halogenation with N-halosuccinimide (NXS) as halide source is reported. The synthesis involved the steady in situ generation of highly reactive positive halogen (X+) by the coordination of copper or zinc with the N-halosuccinimide and subsequent electrophilic aromatic substitution of the electron-deficient coumarins. This procedure works well also for the halogenation of less electron-rich naphthoquinones, flavones, and methoxypsoralen in moderate to quantitative yields. This protocol features simple experimental conditions using readily available inexpensive reagents and provides a convenient approach to the chlorination or bromination of some useful heteroaromatic compounds.

Characterization and Photocatalytic Activity of FeVO4 Photocatalysts Synthesized via a Surfactant-Assisted Sol-Gel Method

2011 ◽  
Vol 197-198 ◽  
pp. 926-930
Author(s):  
Min Wang ◽  
Qiong Liu ◽  
Chen Zhi Jiang
Keyword(s):  
Photocatalytic Activity ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Gel Method ◽  
Sol Gel Method ◽  
Photodegradation Rate ◽  
Photocatalytic Activities ◽  
Xrd Patterns ◽  
Surfactant Assisted

FeVO4photocatalysts were synthesized via a surfactant-assisted sol-gel method and characterized with X-ray diffraction (XRD), scanning electron microsoope （SEM）and specific surface area (BET). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) solution under visible light. The XRD patterns of no-surfactant-assisted, PEG-assisted, CTAB-assisted and SDS-assisted FeVO4, indicate that diffraction peaks can be well indexed as triclinc FeVO4. And the crystalline sizes of samples were evaluated as 113, 69, 66, 76 nm for FVO, FVO-PEG, FVO-CATB and FVO-SDS respectively.The addition of surfactant woul greatly affect the morphology of FeVO4photocatalysts, which can lead to different photocatalytic activities between them. In the experimental conditions used, the PEG-assisted FeVO4product had a much higher photocatalytic activity (the photodegradation rate was about 77% or so in 14h) than the other three products.

Heptafluoroisopropyl diazomethane (i-C3F7CHN2): in situ generation and synthesis of pyrazoles

2017 ◽  
Vol 15 (35) ◽  
pp. 7296-7301 ◽  
Author(s):  
Pavel K. Mykhailiuk
Keyword(s):  
Aqueous Media ◽  
Chemical Reagent ◽  
In Situ Generation

A novel chemical reagent, heptafluoroisopropyl diazomethane (i-C3F7CHN2), has been generated in situ in aqueous media. It reacts with electron-deficient alkynes towards polyfluorinated pyrazoles that are important in agrochemistry.

Preparation and Properties of PVC-Silica Composites using Different Catalysts Via Sol-Gel Process

1999 ◽  
Vol 576 ◽  
Author(s):  
Khan M. Asif ◽  
M.I. Sarwar ◽  
Z. Ahmad
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Sol Gel ◽  
Silica Network ◽  
Transparent Films ◽  
Sol Gel Process ◽  
Gel Technique ◽  
In Situ Generation ◽  
Scanning Electron

Novel micro-composites from Polyvinyl chloride (PVC) and silica were prepared using sol-gel technique. Different catalysts were used for the in-situ generation of silica network from tetraethylorthosilicate (TEOS) in the PVC matrix. Thin transparent films containing various proportions of silica in PVC were cast by the solvent elution technique. Mechanical properties of these films were studied. The results showed an increase in the value of Young's modulus and strain at rupture by the addition of small amount of silica in PVC. However, the stress at yields point and stress at rupture decreased with the addition of silica contents. Scanning electron microscopy (SEM-EDAX) studies were also performed on these samples.

scholarly journals The Effect of Precursors Concentration on the Structure and Micromagnetic Properties of Ultrafine Iron Oxides Obtained by Sol-Gel Route

2016 ◽  
Vol 3 (1) ◽  
pp. 38-45
Author(s):  
V. Kotsyubynsky ◽  
A. Hrubiak ◽  
L. Mohnatska ◽  
M. Gasyuk ◽  
V. Moklyak
Keyword(s):  
Phase Composition ◽  
Composite Materials ◽  
Ir Spectroscopy ◽  
Sol Gel ◽  
Iron Nitrate ◽  
Colloidal Solutions ◽  
X Ray Diffraction ◽  
Magnetic Microstructure ◽  
Iron Citrate ◽  
X Ray

Nanodispersed composite materials -Fe2O3/-Fe2O3 were obtained by thermaldecomposition of iron citrate xerogel hydrate synthesized by iron nitrate and citrate acid solutionswith different colloidal solutions of Fe(NO3)39H2O and С6Н8О7 Н2О for different molar ratiobetween precursors. The influence of the precursors molar concentration and calcinationtemperature on the material phase composition, crystalline and magnetic microstructure, surfacecondition was studied. Methods of X-ray diffraction, Mössbauer spectroscopy, electron microscopyand IR - spectroscopy were used.

Preliminary Study of Corrosion Mechanisms of Actinides Alloys: Calibration of FT-IR Spectroscopy

2008 ◽  
Vol 1104 ◽  
Author(s):  
Véronique Magnien ◽  
Marx Cadignan ◽  
Olivier Faivret ◽  
Gaelle Rosa
Keyword(s):  
Ir Spectroscopy ◽  
Accurate Estimation ◽  
Ir Absorption ◽  
Experimental Conditions ◽  
Ft Ir ◽  
Gaseous Atmospheres ◽  
Set Up ◽  
Corrosion Mechanisms ◽  
Ft Ir Spectroscopy

AbstractIn situ analyzes of gaseous atmospheres could be performed by FT-IR spectroscopy in order to study the corrosion reactions of actinides. Nevertheless experimental conditions and the nature of studied species have a strong effect on IR absorption laws. Thus a prior calibration of our set-up is required to obtain an accurate estimation of gas concentration. For this purpose, the behavior of several air pure gases has been investigated according to their concentration from IR spectra. Reproducible results revealed subsequent increases of the most significant peak areas with gas pressure and small deviations from Beer Lambert's law. This preliminary work allowed to determine precise absorption laws for each studied pure gas in our in situ experimental conditions. Besides our FT-IR set-up was well suitable to quantitative analysis of gaseous atmosphere during corrosion reactions. Finally the effect of foreign gas will be investigated through more complex air mixtures to obtain a complete calibration network.

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