Study of Polyethers/Lii Systems by Addition of Alumina Ceramic Powders Prepared by Two Synthesis Methods

1998 ◽  
Vol 548 ◽  
Author(s):  
R. A. Ribeiro ◽  
G. G. Silva ◽  
N. D. S. Mohallem
Keyword(s):  
Sol Gel ◽  
Alumina Ceramic ◽  
Synthesis Methods ◽  
Ceramic Powders ◽  
Scanning Calorimetry ◽  
Dsc Studies ◽  
Lower Melting Point ◽  
Poly Ethylene ◽  
Copolymer Poly ◽  
Co Precipitation

ABSTRACTComposites of alumina ceramic powders prepared by co-precipitation and sol-gel methods with Lithium Iodide based polymer electrolytes are described. The polyether matrices Poly(ethylene oxide) (PEO) and block copolymer Poly(propylene glycol-ethylene glycolpropylene glycol) (Triblock) with Lil in a ratio [O]:[Li] = 20:1 are used with up to 17 wt% of α-A1203 (medium grain size). Differential Scanning Calorimetry (DSC) studies show that Tg values for PEO based composites are higher whereas those for Triblock based composites are lower than the Tg value of the polymer/salt system.Conductivity measurements as a function of temperature show that there is no significant change in conductivity above the melting points for the electrolytes after α-A1203 powder addition (σ approximately 10−3 S.cm−l at 100°C), whereas better mechanical properties are observed for the ceramic reinforced samples. An increase in conductivity is obtained for the Triblock based composites near room temperature as a consequence of the lower melting point of these materials (26°C) in comparison to the PEO based composites (54°C).

scholarly journals Magnetite-Silica Core/Shell Nanostructures: From Surface Functionalization towards Biomedical Applications—A Review

2021 ◽  
Vol 11 (22) ◽  
pp. 11075
Author(s):  
Angela Spoială ◽  
Cornelia-Ioana Ilie ◽  
Luminița Narcisa Crăciun ◽  
Denisa Ficai ◽  
Anton Ficai ◽  
...  
Keyword(s):  
Magnetite Nanoparticles ◽  
Biomedical Applications ◽  
Sol Gel ◽  
Magnetic Nanomaterials ◽  
Core Shell ◽  
Synthesis Methods ◽  
Shell Nanostructures ◽  
Silica Core ◽  
Magnetic Resonance Imaging Mri ◽  
Co Precipitation

The interconnection of nanotechnology and medicine could lead to improved materials, offering a better quality of life and new opportunities for biomedical applications, moving from research to clinical applications. Magnetite nanoparticles are interesting magnetic nanomaterials because of the property-depending methods chosen for their synthesis. Magnetite nanoparticles can be coated with various materials, resulting in “core/shell” magnetic structures with tunable properties. To synthesize promising materials with promising implications for biomedical applications, the researchers functionalized magnetite nanoparticles with silica and, thanks to the presence of silanol groups, the functionality, biocompatibility, and hydrophilicity were improved. This review highlights the most important synthesis methods for silica-coated with magnetite nanoparticles. From the presented methods, the most used was the Stöber method; there are also other syntheses presented in the review, such as co-precipitation, sol-gel, thermal decomposition, and the hydrothermal method. The second part of the review presents the main applications of magnetite-silica core/shell nanostructures. Magnetite-silica core/shell nanostructures have promising biomedical applications in magnetic resonance imaging (MRI) as a contrast agent, hyperthermia, drug delivery systems, and selective cancer therapy but also in developing magnetic micro devices.

Study on Different Synthesis Methods of Spherical YAG:Ce3+ Phosphor and its Luminescence Properties

2015 ◽  
Vol 1088 ◽  
pp. 371-376 ◽  
Author(s):  
Xia Zhang ◽  
Cui Xia Yan ◽  
Rong Feng Guan
Keyword(s):  
Sol Gel ◽  
Spherical Particles ◽  
Luminescence Properties ◽  
Precipitation Method ◽  
Thermal Method ◽  
Synthesis Methods ◽  
Processing Parameter ◽  
Gel Method ◽  
Sol Gel Method ◽  
Co Precipitation

Spherical YAG:Ce3+phosphors were synthesized by three different routes namely sol-gel method, co-precipitation method and solvethermal method. The microstructure, crystallization and luminescent properties of the phosphors were studied in order to find the best processing parameter for spherical shape and good luminescence properties of YAG:Ce3+phosphor. Adding citric acid to the precursor solution resulted in the formation of spherical particles in sol-gel method. YAG:Ce3+phosphor made by co-precipitation method was separated with PEG2000, and its spherical particles of size was around 500nm. The hydro-thermal method could get perfect spherical appearance, but it needed heat treatment improve the luminescence property.

scholarly journals Synthesis Methods of Obtaining Materials for Hydrogen Sensors

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5758
Author(s):  
Izabela Constantinoiu ◽  
Cristian Viespe
Keyword(s):  
Spin Coating ◽  
Sol Gel ◽  
Synthesis Method ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Synthesis Methods ◽  
Sensitive Area ◽  
Hydrogen Sensors ◽  
Hydrogen Detection ◽  
Co Precipitation

The development of hydrogen sensors has acquired a great interest from researchers for safety in fields such as chemical industry, metallurgy, pharmaceutics or power generation, as well as due to hydrogen’s introduction as fuel in vehicles. Several types of sensors have been developed for hydrogen detection, including resistive, surface acoustic wave, optical or conductometric sensors. The properties of the material of the sensitive area of the sensor are of great importance for establishing its performance. Besides the nature of the material, an important role for its final properties is played by the synthesis method used and the parameters used during the synthesis. The present paper highlights recent results in the field of hydrogen detection, obtained using four of the well-known synthesis and deposition methods: sol-gel, co-precipitation, spin-coating and pulsed laser deposition (PLD). Sensors with very good results have been achieved by these methods, which gives an encouraging perspective for their use in obtaining commercial hydrogen sensors and their application in common areas for society.

Innovative Synthesis Methods of Mixed Actinides Compounds with Control of the Composition Homogeneity at a Molecular or Nanometric Scale

2005 ◽  
Vol 893 ◽  
Author(s):  
Stephane Grandjean ◽  
Chapelet-Arab Bénédicte ◽  
Lemonnier Stéphane ◽  
Robisson Anne-Charlotte ◽  
Vigier Nicolas
Keyword(s):  
Thermal Treatment ◽  
Sol Gel ◽  
3D Structure ◽  
Molar Ratio ◽  
Synthesis Methods ◽  
Oxalate Precursor ◽  
Fuel Cycles ◽  
Tetravalent Actinide ◽  
Sol Gel Transition ◽  
Co Precipitation

AbstractActinides contained in the used nuclear fuel need to be managed in the future fuel cycles for the sustainability of this source of energy. The major ones such as uranium or plutonium are very valuable for energy production within a new fuel. The minor ones such as neptunium, americium or curium are responsible for the long-term radiotoxicity of the ultimate waste if not separated and transmuted within new fuels or dedicated targets. Whatever the choice of management in the present or future, innovative synthesis methods are studied in many research institutions to elaborate new actinides based materials.Innovative concepts for future fuels or transmutation targets focus on mixed actinides or mixed actinide-inert element materials. For their synthesis, wet methods fulfill very useful requirements such as flexibility, compatibility with a hydrometallurgical fuel processing, less dissemination of radioactive dusts during processing, and above all a better accessibility to very homogeneous compounds and interesting nanostructures. When dealing with plutonium or minor actinides, this last characteristic is of great importance in order to avoid the so-called “hot spots” and to limit macroscopic defects in the fuel material.In this communication, experimental results are given to illustrate interesting achievements to control the composition or the structure of mixed actinides compounds at a molecular or at a nanometric scale using co-precipitating techniques or sol-gel methods.The first illustration describes the flexibility of the oxalate ligand to modulate the nanostructure of actinides-based solid precursors and obtain mixed actinides oxide following a thermal treatment of the oxalate precursor. New mixed oxalate structures which present original features such as accepting in the same crystallographic site either a tetravalent actinide or a trivalent one are noticeably detailed. Monocharged cations equilibrate the charge in the 3D structure depending on the molar ratio of trivalent to tetravalent actinides. These oxalate compounds are particularly suitable precursors of oxide solid solutions for various actinides systems.The second illustration deals with the control of inorganic condensation reactions of tri- and tetravalent cations in solution by using suitable ligands with a view to obtaining homogeneous oxy-hydroxyde mixtures. The results obtained using Zr(IV), Y(III) and Am(III) or Nd(III) are quite original: a very stable colloidal sol is obtained at pH 5-6 and a nanostructured mixed oxy-hydroxide phase is formed by adapting the sol-gel transition conditions. The initial interactions between the oxy-hydroxide Zr nanoparticles, the ligand and the trivalent cations at a nanometric scale in the sol give access, after gel formation and thermal treatment, to a crystallized phase (Am-bearing cubic Y-stabilized Zirconia) at comparatively low temperatures.In both cases, the simultaneous co-precipitation or co-gelation of the involved actinides remains a challenge because of the specific properties of each actinide, properties which moreover differ according to various possible oxidation states.

scholarly journals Comparative studies on impact of synthesis methods on structural and magnetic properties of magnesium ferrite nanoparticles

2014 ◽  
Vol 8 (3) ◽  
pp. 137-143 ◽  
Author(s):  
Navneet Kaur ◽  
Manpreet Kaur
Keyword(s):  
Sol Gel ◽  
Thermolysis Product ◽  
Ferrite Nanoparticles ◽  
Precipitation Method ◽  
Synthesis Methods ◽  
Magnesium Ferrite ◽  
Solution Combustion ◽  
Magnetic Parameters ◽  
Physical Density ◽  
Co Precipitation

Magnesium ferrite nanoparticles (NPs) were synthesized by co-precipitation, sol-gel and solution combustion methods. Polyethylene glycol (PEG), urea and oxalyl dihydrazide (ODH) were used as fuels for the combustion. Various physicochemical techniques viz. X-ray diffraction (XRD), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FT-IR), BET surface analysis and transmission electron microscopy (TEM) were utilized to study the effect of synthetic methodology on the properties of synthesized NPs. Differences in crystallinity, surface area, particle size and magnetic parameters of the ferrite NPs synthesized by different methods were observed. XRD pattern of NPs obtained by sol-gel and combustion methods confirmed phase purity where as in co-precipitation method ?-Fe2O3 was detected as impurity phase which also resulted in greater value of physical density and lowering of magnetic parameters of the final thermolysis product. TEM micrographs indicated that ferrite NPs are spherical with average diameter of 12-25 nm. Presence of rectangular shaped crystallites of ?-Fe2O3 was clearly evident in the TEM images of the NPs synthesized by co-precipitation method.

Sol-gel synthesis of silica–based mesoporous powders

2004 ◽  
Vol 848 ◽  
Author(s):  
Lidia Armelao ◽  
Gregorio Bottaro ◽  
Renzo Campostrini ◽  
Stefano Gialanella ◽  
Marco Ischia ◽  
...  
Keyword(s):  
Sol Gel ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Structure Directing Agent ◽  
Template Removal ◽  
Guest Species ◽  
Poly Ethylene Oxide ◽  
Acidic Conditions ◽  
Poly Ethylene ◽  
Sol Gel Synthesis

ABSTRACTMesoporous silica powders have been synthesized starting from aqueous solutions of Si(OCH2CH3)4 (TEOS) under acidic conditions, using non-ionic alkyl poly(ethylene oxide) oligomer (Brij76) as a structure-directing agent. Template removal was performed by thermal treatment in air as well as by ethanol extraction. The annealing process (400 - 600°C) resulted in more efficient elimination of the organic molecules, thus yielding hexagonal (p6mm) mesopor-ous materials with pore volume and specific surface area ranging between 0.58 – 0.41 cm3/g and 900 – 700 m2/g, respectively. The systems were characterized by X-Ray Diffraction (XRD), N2 BET adsorption, Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Particular attention was focused on the evolution of the system mesostructural and porous features as a function of the template removal procedure. The obtained mesoporous networks are suitable as matrices for the development of nanocomposite systems in which the dispersion or the growth of various guest species (clusters, molecules…) can be addressed into the host mesopores.

scholarly journals Flexible Epoxy Resins Formed by Blending with the Diblock Copolymer PEO-b-PCL and Using a Hydrogen-Bonding Benzoxazine as the Curing Agent

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 201 ◽  
Author(s):  
Wei-Chen Su ◽  
Fang-Chang Tsai ◽  
Chih-Feng Huang ◽  
Lizong Dai ◽  
Shiao-Wei Kuo
Keyword(s):  
Hydrogen Bonding ◽  
Diblock Copolymer ◽  
Mechanical Analysis ◽  
Intermolecular Hydrogen Bonding ◽  
Curing Agent ◽  
Thermal Curing ◽  
Scanning Calorimetry ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Copolymer Poly

In this study, we enhanced the toughness of epoxy resin by blending it with the diblock copolymer poly(ethylene oxide–b–ε-caprolactone) (PEO-b-PCL) with a benzoxazine monomer (PA-OH) as the thermal curing agent. After thermal curing, Fourier transform infrared spectroscopy revealed that intermolecular hydrogen bonding existed between the OH units of the epoxy–benzoxazine copolymer and the C–O–C (C=O) units of the PEO (PCL) segment. Differential scanning calorimetry and dynamic mechanical analysis revealed that the glass transition temperature and storage modulus of the epoxy–benzoxazine matrix decreased significantly upon increasing the concentration of PEO-b-PCL. The Kwei equation predicted a positive value of q, consistent with intermolecular hydrogen bonding in this epoxy–benzoxazine/PEO-b-PCL blend system. Scanning electron microscopy revealed a wormlike structure with a high aspect ratio for PEO-b-PCL as the dispersed phase in the epoxy–benzoxazine matrix; this structure was responsible for the improved toughness.

Effect of Synthesis methods on the Properties of Magnetic Material

2015 ◽  
Vol 10 (1) ◽  
pp. 2566-2582
Author(s):  
Anwar Ul Haq ◽  
Farwa Mushtaq ◽  
M. Anis-ur-Rehman
Keyword(s):  
Sol Gel ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Basic Material ◽  
Synthesis Methods ◽  
Hydraulic Pressure ◽  
Phase Purity ◽  
Gel Method ◽  
Sol Gel Method ◽  
Co Precipitation

Ba1-xPbxFe12O19 composition (x=0.0 to 1.0) synthesized by Co-precipitation and Sol-Gel  methods. In Co-precipitation method BaCO3, PbO and Fe (NO3)3 .9H2O were used as basic ingredients. Acids and Di-H2O  were used as solvents. Molar ratio of cations was 12.   pH of solution kept constant at 13.  All samples sintered at 965±5oC for three hours.  Lead own properties, synthesis at room temperature and substitution in R-block of structure were the reasons for decrease of phase purity from “x” =0.0 to 70% for “x”=1.0. Decrease in phase purity   and heterogeneity of material caused the properties to decrease. In Sol gel method, Nitrates (salts) and Ethylene glycol (liquid) were the basic material used. The mixed solutions dried out on a hot plate whose temperature was maintained constant at 200±2oC. Pellets formed by applying suitable hydraulic pressure and then sintered at same temperature written above i.e. 965±5oC for three hours. 100% phase purity achieved. All properties modified. Temperature and frequency dependent electrical properties investigated and reported here. DC and AC obtained properties were useful for different electronics and computer devices like capacitors, smart storage devices and multilayer chip inductors. Overall, both these properties improved through sol-gel method as compared to co-precipitation method. It was because of improvement in phase purity and change in morphology of synthesized material. 

scholarly journals Green Synthesis and Applications of ZnO and TiO2 Nanostructures

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2236
Author(s):  
Rosana A. Gonçalves ◽  
Rosimara P. Toledo ◽  
Nirav Joshi ◽  
Olivia M. Berengue
Keyword(s):  
Green Synthesis ◽  
Sol Gel ◽  
Cost Effective ◽  
Synthesis Methods ◽  
Green Approach ◽  
Oxide Nanostructures ◽  
Co Precipitation ◽  
Physical And Chemical ◽  
Synthesis Approach ◽  
Tio2 Nanostructures

Over the last two decades, oxide nanostructures have been continuously evaluated and used in many technological applications. The advancement of the controlled synthesis approach to design desired morphology is a fundamental key to the discipline of material science and nanotechnology. These nanostructures can be prepared via different physical and chemical methods; however, a green and ecofriendly synthesis approach is a promising way to produce these nanostructures with desired properties with less risk of hazardous chemicals. In this regard, ZnO and TiO2 nanostructures are prominent candidates for various applications. Moreover, they are more efficient, non-toxic, and cost-effective. This review mainly focuses on the recent state-of-the-art advancements in the green synthesis approach for ZnO and TiO2 nanostructures and their applications. The first section summarizes the green synthesis approach to synthesize ZnO and TiO2 nanostructures via different routes such as solvothermal, hydrothermal, co-precipitation, and sol-gel using biological systems that are based on the principles of green chemistry. The second section demonstrates the application of ZnO and TiO2 nanostructures. The review also discusses the problems and future perspectives of green synthesis methods and the related issues posed and overlooked by the scientific community on the green approach to nanostructure oxides.

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