Ultra-light pours hydrophilic silica were prepared by sol gel neutralization chemical method under the ambient temperature under the effect different molar ratio of oxalic acid (1, 2, and 3), to study its effect on the structure of silica aerogel based on water glass (Na2SiO3. 5H2O) used as the precursors. The gel was washed with deionized distilled water four times for 24 hours. The pH of the gel has a constant value of about 8. Time gelation occurs during (10-25) minutes depending on the acidic molar ratio. The diagnostic analysis is taken by Fourier transition infrared (FTIR), field emission scanning electron microscope (FESEM), and X-ray diffraction (XRD). The material products have a lightweight with low density (0.35 – 0.27) gm/cm 3, It was floating in the water by its low weight despite its hydrophilic characteristic property. All the diagnostic results matching conformity to most published research results which will also be explained in the present study
Polycrystalline CaBi4Ti4O15 (CBT) ceramics were successfully prepared by traditional ceramic technique. The X-ray diffraction spectrum of produced powder was studied at different temperatures (650 C, 850 C, and 1050C. The sintering temperature is very effective factor to obtained high crystallinity with very pure for CBT compound. The product structures analyzed using X-ray diffraction, it confirms, high purity polycrystalline phase formation revealed the existence of bismuth layered perovskite phase Aurivillius orthorhombic crystal structure at 1050ᶹ C. The produced samples' A field emission scanning electron microscope was used to analyze the morphologies (FESEM). It shows crystallites particles in the range about 149-349 nm for the product sintered at1050ᶹ C, it shows a dense microstructure with the presence of large orthorhombic distortion. The dielectric constant and dielectric loss were measured at room temperature as a function of frequency. The dielectric constant of CBT increases in sintering temperature. Moreover, the samples sintered at 1050 ᶹC exhibits good dielectric properties and lower value of tan .
The chemical formula Li0.5Fe2.5O4 of lithium ferrite prepared by two different chemical methods mentioned as low temperature solid state reaction (LTSSR) and modified combustion method (MCM). The samples showed nanoparticle scale with spinal structure. The magnetic analyses have done by the vibrating sample magnetometer VSM device, and both samples have the same magnetic properties represented by the magnetic saturation, remanence magnetization, and coercive magnetic field. The shape of hysteresis loop showed a soft ferrite and its area decreased with temperature increasing. On the other hand, the magnetic susceptibility decreased with increasing temperature for both samples of ferrite Li0.5Fe2.5O4 prepared. The sample of LTSSR exhibited a magnetic moment of about 0.410-3 JT-1 at applied magnetic field 50 kOe which is approaching the same for the sample prepared by MCM method.
In the present work, nonporous hydrophilic unmodified silica aerogel was synthesized successfully by ambient drying with one step base catalyst by used silica organic initiator tetraethoxysilane (TEOS). Silica aerogel was prepared twice by sol-gel technique; the first one was the gelation that happened under the alkaline catalyst NH4OH, which has a toxic property and dangerous to human health. The second gelation under the effect of the safety inorganic base catalyst sodium silicate (water glass) that used as an inorganic low-cost and environmentally friendly initiator to silica, plays a role in increasing pH as a catalyst and as a new rare co-precursor mixing organic and inorganic silica precursors (TEOS+Na2SiO3). The impurities accompanying water glass and sodium residue were eliminated by a lot of washing. The volume ratio of the (TEOS: ethanol: H2O: base catalyst) fixed respectively at (5.6:50:10:0,01M). The gelation reaction time, the gel properties, it's quality and the amount of the reactant, the density, and the appearance all effect by the type of catalyst used. The comparative study of silica porous aerogel production properties diagnostic achieved by FTIR, XRF, BET, BJH, FESEM and thermal conductivity applied as insulation materials .
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