scholarly journals Synthesis of Silica Nanostructures and Optimization of their Size and Morphology by Use of Changing in Synthesis Conditions

2012 ◽  
Vol 9 (2) ◽  
pp. 659-668 ◽  
Author(s):  
A. Elsagh
Keyword(s):  
Drug Delivery Systems ◽  
Sol Gel ◽  
Molar Ratio ◽  
Synthesis Conditions ◽  
Acid Type ◽  
Silica Nanostructures ◽  
Size And Morphology ◽  
Sol Gel Synthesis ◽  
Optimized Conditions ◽  
Cracking Products

The aim of the present research was optimization of practical conditions of the sol-gel synthesis. In so doing, silica particles were synthesized using sol-gel method and their size and morphology were investigated by use of SEM and TEM images. The effect of changing molar ratio of reactive including acids and silica pre-matter on the particles' morphology and size was studied. Also, acid type and silica pre-matter used in reaction was examined and the result product of the reaction were investigated in the presence of several acids and two types of silica pre-matter. The reaction time was studied as a very important factor in products' digestion phase which plays a significant role in determining particles’ size and rate of cracking products. Finally, in optimized conditions 50-80 nm diameter nanostructures were synthesized. These products can be used as drug delivery systems.

Effect of the Sol-Gel Synthesis Parameters on the Incorporation of an Anti-inflammatory Drug in a Ceramic Material

2007 ◽  
Vol 1007 ◽  
Author(s):  
Aracely Hernandez ◽  
Patricia Esquivel-Ferriño ◽  
Idalia Gomez ◽  
Lucia Cantu
Keyword(s):  
Ceramic Material ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Molar Ratio ◽  
Inflammatory Drug ◽  
Synthesis Conditions ◽  
Synthesis Parameters ◽  
Anti Inflammatory ◽  
Drug Incorporation ◽  
Sol Gel Synthesis

ABSTRACTIn the present work, sol-gel method was used to incorporate in a ceramic material a non steroidal anti-inflammatory drug (piroxicam) as model drug. The incorporation of the drug in the SiO2 network was carried out at different sol-gel synthesis parameters, such as pH (3 and 5) and the alkoxide/water ratio (1:6 and 1:8). The biomaterial obtained was analyzed by thermal analysis TGA-DTA, infrared spectroscopy (FTIR), Scanning Electronic Microscopy (SEM) and X-ray diffraction (XRD); specific surface area and porosity were analyzed from nitrogen adsorption isotherm. Better drug incorporation into the material was achieved at the synthesis conditions of pH 5 and 1:6 alkoxide/water molar ratio.

Sol-Gel Synthesis and Characterization of Ultrafine ZrSiO4 Powder

2014 ◽  
Vol 906 ◽  
pp. 66-71
Author(s):  
Zhen Quan Li ◽  
Qiang Zhen ◽  
Ya Li Wang
Keyword(s):  
Wavelength Range ◽  
High Purity ◽  
Raw Materials ◽  
Formation Rate ◽  
Sol Gel ◽  
Molar Ratio ◽  
Sem And Tem ◽  
Homogeneous Product ◽  
Sol Gel Synthesis ◽  
Calcined Temperature

High purity ZrSiO4 powder were synthesized using Si (C2H5O)4 and ZrOCl2·8H2O as raw materials by the sol-gel method, LiCl was added as mineralizer to promote crystallization of zircon. The influences of molar ratio of Zr:Si, calcined time and calcined temperature on the synthesis of ZrSiO4 powder were investigated. XRD, SEM and TEM were used to characterize the powders. It was found that when the molar ratio of Zr:Si was 1:1.2, the calcined temperature was 1600°C and the calcined time was 4h, the high purity ZrSiO4 ultrafine powder was obtained. The ZrSiO4 formation began at 1300°C and when the gel was calcined at 1600°Cfor 4 h, the formation rate of ZrSiO4 was up to 95%. SEM and TEM studies reveal a homogeneous product with particle sizes on the order of 0.1-1μm. The IR emissivity of ultrafine ZrSiO4 is 0.892 at the whole wavelength range, and that is up to 0.951 at the wavelength range of 8-14 μm.

Sol-gel synthesis and characterization of Ag nanoparticles in ZrO2 thin films

2009 ◽  
Vol 24 (8) ◽  
pp. 2541-2546 ◽  
Author(s):  
Eisuke Yokoyama ◽  
Hironobu Sakata ◽  
Moriaki Wakaki
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Composite Films ◽  
Dip Coating ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Silver Surface ◽  
Molar Ratios ◽  
Sol Gel Synthesis

ZrO2 thin films containing silver nanoparticles were prepared using the sol-gel method with Ag to Zr molar ratios [Ag]/[Zr] = 0.11, 0.25, 0.43, 0.67, 1.00, 1.50, and 2.33. After dip coating on glass substrate, coated films were annealed at 200 and 300 °C in air. X-ray diffraction peaks corresponding to crystalline Ag were observed, but a specific peak corresponding to ZrO2 was not observed. At the molar ratio [Ag]/[Zr] = 0.25, the particle size of Ag distributed broadly centered at 17 nm for an annealing temperature of 200 °C and at 25 nm for 300 °C. The films annealed in air at 200 °C showed an absorption band centered at 450 nm because of the silver surface plasmon resonance, whereas films heated at 300 °C in air caused a red shift of the absorption to 500 nm. The absorption peak was analyzed using the effective dielectric function of Ag-ZrO2 composite films modeled with the Maxwell-Garnett expression.

Effect of acidity on the properties of silica-aluminas synthesized by sol-gel method

2020 ◽  
Vol 63 (7) ◽  
pp. 126-132
Author(s):  
Lyubov V. Furda ◽  
◽  
Evgenia A. Tarasenko ◽  
Sofya N. Dudina ◽  
Olga E. Lebedeva ◽  
...  
Keyword(s):  
Surface Area ◽  
Sol Gel ◽  
Molar Ratio ◽  
Active Centers ◽  
Indicator Method ◽  
Synthesis Conditions ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
Amphoteric Properties ◽  
Hydrolysis Of

In the present work amorphous silica-aluminas were synthesized by the coprecipitation method during the hydrolysis of an alcohol solution of tetraethoxysilane (with a tetraethoxysilane: alcohol mass ratio of 1: 1) and 6% aqueous solution of aluminum nitrate at pH values of 1, 3, and 10. The Si/Al molar ratio for all synthesized samples were 4.72 (± 0.29). The amorphous character of the investigated materials was confirmed by X-ray phase analysis. According to the results of scanning electron microscopy, it was found that the resulting powders have particles with a size of 1-20 μm. It was shown that the conditions of synthesis affected the specific surface area and porosity of the materials under study. By the method of low-temperature adsorption-thermodesorption of nitrogen it was established that silica-aluminas obtained under acidic conditions were microporous materials. For the sample obtained under alkaline conditions (pH = 10), the contribution of macropores is very significant. A decrease in surface area is observed as the pH of the synthesis increases. The Hammett indicator method was used to identify and quantify surface centers of different acidity. All studied silica-aluminas are characterized by the presence of both Brønsted basic (pKax from 7 to 12.8) and acidic (pKax from 0 to 7) centers, and Lewis basic (pKax from -4.4 to 0) with a pronounced maximum at pKax = 1.02. It was found that the synthesis conditions had a significant effect on the concentration of active centers. The values of the Hammett function are practically the same for the 3 studied silica-aluminas and describe the studied samples as materials of medium acidity. The variety of Lewis and Brønsted centers on the surface indicates the amphoteric properties of the materials under study. This gives the samples the properties of polyfunctional sorbents and catalysts.

Effect of sol–gel synthesis conditions on the physical properties of silica hydrogels

2020 ◽  
Vol 30 (6) ◽  
pp. 812-814
Author(s):  
Ekaterina S. Dolinina ◽  
Anton S. Kraev ◽  
Elena V. Parfenyuk
Keyword(s):  
Physical Properties ◽  
Sol Gel ◽  
Synthesis Conditions ◽  
Silica Hydrogels ◽  
Sol Gel Synthesis

Synthesis and Magnetic Properties of FePt Nanoparticles with Hard Nonmagnetic Shells

2007 ◽  
Vol 7 (1) ◽  
pp. 350-355 ◽  
Author(s):  
Shishou Kang ◽  
Shifan Shi ◽  
G. X. Miao ◽  
Zhiyong Jia ◽  
David E. Nikles ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Crystallographic Orientation ◽  
Sol Gel ◽  
Molar Ratio ◽  
Core Shell ◽  
Fept Nanoparticles ◽  
Shell Nanoparticles ◽  
Spherical Core ◽  
Size And Morphology ◽  
Core Shell Nanoparticles

Chemically synthesized FePt nanoparticles were coated with nonmagnetic SiO2 and MnO shells by sol–gel and polyol processes. TEM images show that the FePt/SiO2 nanoparticles exhibit a thick spherical shell. The size and morphology of the MnO shell can be controlled by changing the reaction temperature, the molar ratio of surfactants/Mn(acac)2, and/or the concentration of precursor. The morphology of the MnO shell can be either spherical-like or cubic-like, depending on whether the molar ratio of surfactants/Mn(acac)2 is less than or larger than 2. From XRD measurements, the spherical core/shell nanoparticles exhibit 3D random crystallographic orientation, while the cubic core/shell nanoparticles prefer (200) texture. The magnetic moment of FePt particles can be enhanced by coating with SiO2 and MnO shells. Furthermore, the agglomeration of FePt particles upon the thermal annealing can be significantly inhibited with SiO2 and MnO shells.

Effect of Sintering Time on the Phase Composition in PFN Ceramics Prepared by Sol-Gel Process

2009 ◽  
Vol 409 ◽  
pp. 317-321 ◽  
Author(s):  
Helena Bruncková ◽  
Ľubomír Medvecký ◽  
Ján Mihalik
Keyword(s):  
Perovskite Phase ◽  
Sol Gel ◽  
Pyrochlore Phase ◽  
Molar Ratio ◽  
Sintering Time ◽  
Sol Gel Process ◽  
Sol Gel Synthesis ◽  
Spherical Grains ◽  
Bimodal Grain Size ◽  
Iron Niobate

Lead iron niobate Pb(Fe0.5Nb0.5)O3 (PFN) ceramics were prepared using sol-gel synthesis by mixing acetates Pb and Fe with Nb-ethylene glycol-tartarate (Pechini) complex at 80°C, calcination of gels at 600°C and sintering at 1150°C for various times. The metastable pyrochlore phase Pb3Nb4O13 in stoichiometric precursor was partially decomposed to perovskite phase Pb(Fe0.5Nb0.5)O3 in ceramics sintered at temperature of 1150°C for 2, 4 and 6 hours. Excess of Pb in molar ratio (Pb:Fe:Nb = 1.2:0.5:0.5) caused the increase of the content of the perovskite phase (~50 vol.%) in nonstoichiometric PFN ceramics sintered at 1150°C for 6 hours while the decrease in perovskite phase content was found in stoichiometric PFN ceramics (~16 vol.%). In microstructures of PFN ceramics sintered at 1150°C for different times, the bimodal grain size distribution was observed with small spherical grains of perovskite phase and larger octahedral grains of pyrochlore phase. EDX analysis confirm that complex types of pyrochlore phases that differ in iron content were present in ceramics.

Morphology and Phase Composition of Sol-Gel Derived Aluminum Borate Nanowhiskers

2015 ◽  
Vol 659 ◽  
pp. 121-126 ◽  
Author(s):  
Pat Sooksaen
Keyword(s):  
Fourier Transform ◽  
Phase Composition ◽  
Sol Gel ◽  
Molar Ratio ◽  
Aluminum Borate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Higher Temperature ◽  
Sol Gel Synthesis ◽  
Scanning Electron

Aluminium borate nanowhiskers with varying aspect ratio were synthesized via sol–gel synthesis. The morphology of aluminum borate (Al4B2O9 and Al18B4O33) nanowhiskers could be controlled by varying the aluminum to boron (Al:B) molar ratio in the sol–gel derived precursors. Sintering temperatures (850 and 1100°C) and sintering times (4 and 32 hours) also affected the phase composition and size of the nanowhiskers. Citric acid was also added in the sol–gel derived precursors as a surface stabilizer for obtaining uniform finely dispersed nanostructures. Fine nanowhiskers were obtained by the calcination at 850°C, whereas higher temperature of 1100°C led to thicker and longer nanowhiskers and became rod-like crystals. The morphology and phase composition were investigated by field emission scanning electron microscope and X-ray diffraction. Chemical bond vibrations in the synthesized nanowhiskers were investigated by Fourier-transform infrared spectroscopy.

scholarly journals Sol-Gel Synthesis, Magnetic and Optical Properties of Co2+:Nd3+::2:1 molar ratio doped in SiO2

2015 ◽  
Vol 11 (3) ◽  
pp. 3367-3374
Author(s):  
Bidhu Bhusan Das ◽  
Ruppa Govinda Rao
Keyword(s):  
Magnetic Moments ◽  
Sol Gel ◽  
Broad Band ◽  
Molar Ratio ◽  
Amorphous Sio2 ◽  
Asymmetric Mode ◽  
Distorted Octahedral ◽  
Bending Mode ◽  
Sio2 Phase ◽  
Sol Gel Synthesis

Synthesis of Co2+:Nd3+::2:1 molar ratio doped SiO2 with Co2+ ions concentrations viz. 0.0004, 0.001,  0.002, 0.003, 0.004 moles in S1-S5, respectively are performed by sol-gel method. Observed values of the densities and the concentrations of the Co2+ ions in S1-S5 are found to be 2.26, 2.29, 2.37, 3.44, 2.49 g/cm3, and ~ 1020 ions/g, respectively. Powder XRD results show the formation of amorphous SiO2 phase in the samples. DTA-TGA/DTG traces in the range 27-700 ˚C show no characteristic event in the samples. The IR peak in the range 412-418 cm-1 is ascribed to the asymmetric mode of the octahedral [NdO6/2]3- units. The peak around 440 cm-1 in S1-S5 is due to the ν2-symmetric bending mode of the tetrahedral [SiO4/2]4- units. The weak IR peak ~ 670 cm-1 is due to the ν1-mode of the tetrahedral [CoO4/2]4- units. The calculated values of the magnetic susceptibility from the observed magnetic moments data at 300 K are found to be ~10-6  emu/gG in S1-S5 which show the weak paramagnetic nature of the materials.  The EMR lineshapes recorded at 6, 50, 77, and 300 K are very broad, isotropic and smeared out with only two detectable characteristic peaks. The giso-value ~ 2.3 is due to the doped Co2+(3d7) ions in tetrahedral coordinations, while the giso-value ~ 2.01 is due to the doped Nd3+(4f3) ions in distorted octahedral coordinations. The lineshapes only at 6 K are distinct, while at higher temperatures  these peaks are severely smeared out. The optical absorption broad band at ~750 nm (13262 cm-1) is assigned to 4I9/2 ® 4F7/2 + 4S3/2 transitions in optically active Nd3+(4f3) ions, and the  peak ~ 520 nm (19230 cm-1) is attributed to 4A2g ® 4T1g(P) transitions in Co2+ (S=3/2, 3d7) ions in tetrahedral coordinations.

scholarly journals Effect of Carbon Sources and Synthesis Conditions on the LiFePo4/C Cathode Properties

2018 ◽  
Vol 57 (2) ◽  
pp. 183-192 ◽  
Author(s):  
R.R. Kapaev ◽  
S.A. Novikova ◽  
A.A. Chekannikov ◽  
D.Yu. Gryzlov ◽  
T.L. Kulova ◽  
...  
Keyword(s):  
Discharge Capacity ◽  
Polyvinylidene Fluoride ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Carbon Sources ◽  
Water Mixture ◽  
Synthesis Conditions ◽  
Size Growth ◽  
Graphite Structure ◽  
Sol Gel Synthesis

Abstract The sol-gel synthesis and precipitation from dimethyl sulfoxide (DMSO)-water mixture were used to obtain LiFePO4. Sucrose (sucr), citric acid (CA), phthalic acid (phth), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PVDF), polyethylene glycol (PEG), polyacrylic acid (PAA) were investigated as carbon precursors. Increasing of the annealing temperature from 600 °» to 800 °» leads to a certain perfection of graphite structure with simultaneous particle size growth. Higher capacities were observed for the materials synthesized at 600 °». The best results for the sol-gel synthesis were obtained when PVDF was used as a source of carbon coating due to the partial fluorination of LiFePO4 (discharge capacity of LiFePO4/ C-PVDF was ~160 and 70 mAh g-1 at 20 mA g-1 and 800 mA g-1 currents, respectively). For nanocrystalline LiFePO4 obtained by precipitation from DMSO-water mixture the best results were obtained when PEG was used as carbon source (discharge capacity LiFePO4/C-PEG was 158 and 77 mAh g-1 at 20 mA g-1 and 800 mA g-1, respectively).

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