Papers by Keyword: Sol-Gel

Abstract: The aim of this study was to compare the synthesis process of magnetic silica nanoparticles (Fe-SNP) through the analysis of X-ray Diffraction (XRD) results. Fe₃O₄ magnetic nanopowders was synthesized by ultrasonic assisted co-precipitation and Fe-SNP was synthesized by direct mixing method of sodium silicate (Na₂SiO₃) and magnetite (Fe₃O₄) and the sol-gel method. Silica sludge was used as a silica source from Indonesia geothermal power plant waste. The synthesized of Fe-SNP is the functionalization of Fe₃O₄ with silica. Variations concentration of Na₂SiO₃ is used for the direct mixing method and variations of Fe₃O₄ form is used for the sol-gel method. Particles formed and particle size were characterized by XRD. The XRD results showed that there is no SiO₂ phase in the sample synthesized by direct mixing method while two phases of SiO₂ and Fe₃O₄ were found in the sample synthesized by sol-gel method. The size of the Fe₃O₄ nanoparticles calculated with Scherer’s formula and it obtained 19.9 nm, while the Fe₃O₄ nanoparticles with the addition of 20 mL and 6 mL Na₂SiO₃ concentrations were 6,53 nm and 10,23 nm. For the sol-gel method the size of Fe₃O₄ nanoparticles obtained was 11,03 using Fe₃O₄ powders and 9,86 using Fe₃O₄ solutions.

Abstract: The annealing temperature dependent on the structural and magnetic properties of hematite (α-Fe₂O₃) powders synthesized via the sol-gel method was studied. The sol-gel method is used to prepare nanoparticles for this experiment. The annealing treatment of 200°C, 400°C, 600°C, and 800°C has been carried out to modify the physical properties. The obtained nanoparticles are characterized by their structural properties using X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. Then, magnetic properties were evaluated using Vibrating Sample Magnetometer (VSM). XRD results have shown an increase in crystallite size with an increase in annealing temperature from 35.10 nm to 60.17 nm. The increase in crystallite size can be attributed to the increase in the crystal structure’s internal energy, which promotes atomic diffusion. The FTIR results show an absorption that appears at the peak around ~530 cm^-1. It indicates that the Fe³⁺ cation has successfully formed. The VSM results show an increase in the value of H_c with an increase in the annealing temperature from 117 Oe to 461.5 Oe. It is supported by the increase of anisotropy constant and increasing temperature annealing.

Abstract: Hybrid (inorganic- organic) glass is an emerging material for engineering applications like protection and functional coatings. This material is very brittle and cannot stand mechanical loads. In this work, multi-wall carbon nanotubes were suggested as a reinforcing material to toughen the hybrid glass. Sol-gel method was used to prepare the hybrid glass (melting glass) by mixing two alkoxysilanes precursors, mono-substituted and di-substituted alkoxysilanes. Four weight ratios (0.0125, 0.025, 0.05, 0.25 wt%) of multi-wall carbon nanotubes were employed. The composite coatings were synthesized by mixing multi-wall carbon nanotubes with the sol once and with the gel another route. The mechanical, structural and functional properties to the yield composite films were characterized. The results showed that the addition of multi-wall carbon nanotubes to the hybrid glass has lowered the wettability of the resulting composite, where the maximum contact angle (θ) was 102°. Besides, existing of multi-wall carbon nanotubes in the matrix has increased the hardness of the hybrid glass to about 43 MPa at 0.0125 wt%. Correspondingly, the fracture toughness (k_IC) has decreased in comparison to the hybrid glass alone. This refers to lower the glass ability to absorb the energy of fracture. The optical transmission has reduced as the weight ratio of multi-wall carbon nanotubes increased.

Abstract: This article is focused to investigate the corrosion resistance of LCC, ULCC and NCC. Castables microstructure is one of the key factors influencing corrosion resistance, therefore new fine matrix was designed. Potassium carbonate was used as a corrosive medium using static crucible method for tested castables. The corrosion mechanism was evaluated by Scanning Electron Microscopy (SEM) with EDX probe. The experimental results disclosed that corrosion resistance was improved with decreasing calcium oxide content of tested castables.

Abstract: Spinel ferrites nanoparticles have attracted the attention of researcher for memory storage devices. We have synthesized MgFeO₄ pure sample and MgFe_1.8Sm_0.2O₄ doped sample via solgel technique. The study of structural, electrical, dielectric, and I-V properties were studied of synthesized spinel magnesium ferrites nanoparticles. X-ray diffraction (XRD) confirmed the spinel structure of both compositions. The frequency dependent AC conductivity, dielectric constant, dielectric tangent loss, was studied in the range of 20Hz to 3MHz. I-V measurements has been done for the resistive switching properties. I-V curves of both compositions in the current study exhibits the formation of hysteresis loop. The hysteresis loop behavior shows that with the addition of samarium the trend of loop increases which plays crucial role as a Resistive Random-Access Memory (ReRAM) application in switching memory storage devices.

Abstract: Thin films of Nickel-doped ZnO have been prepared by sol-gel spin coating process. The doping concentration of Ni by weight has been adjusted as 0%, 2% and 5% .In order to examine the effect of doping on the optical properties , ZnO thin films has been characterized by UV-Vis spectroscopy, this shows Nickel doping affects the transmission in regards to the thin films and the band gap. The observed value of gap energy for 2% of Ni by weight is 3.25eV; also, the urbach energy value of “EU” is contrast with the values of energy gap.For ZnO powder nanostructures, we studied the microstructural and morphological properties, it have been characterized by optical microscope and first-principals computing. The ZnO replicas were clearly observed, the band structure and density of states of phase of crystal ZnO computed using Ab Initio methods, confirmed that pure ZnO is a direct band gap semiconductor for B3 phase, whose phase B3 is of ZnS type Blende.

Abstract: In material science, doping method is employed to produce nanoferrites with desired characteristics. Recently, cobalt doped iron oxide nanomaterials have gained importance in industry for multiple electronic/electrical applications. Large number of methods have been adopted for the synthesis of nanoparticles (NPs), but high manufacturing cost, uniform sized, and anisotropic behaviors limit the commercial applications. In the presented work, cobalt doped (Co-Fe nanomaterials) are developed by a cost-effective sol-gel approach. The doped cobalt ferrites NPs (1%, 2%, and 3% doping of cobalt) were prepared and characterized by XRD, SEM & TEM, FTIR, and VSM techniques. XRD and microscopic (SEM & TEM) analysis revealed synthesis of hexagonal structured cobalt ferrite sized from ~16nm to ~8nm, with the increasing doping pattern of Cobalt from 1% to 3%. FTIR analysis showed the formation of well-structured oxides, which is in strong agreement with XRD and microscopy techniques. Moreover, VSM analysis revealed that cobalt ferrite nanoparticles possess ferromagnetic properties with Ms, Mr and Hc values of 0.038emu/g, 0.005emu/g and 405.19Oe respectively. In addition, squareness (Mr/Ms = 0.16) indicates the presence of single domain spherical particles.

Abstract: Energy storage devices are the demand of the new era for flexible portable electronics. Considering the importance of renewable energy and environmental issues. We utilized LiCo_1-xZn_xO₂ (x=0.0, 0.1) nanoparticles with an average crystallite size of 31-45nm that were embedded in nanofibers formed by the electrospinning technique. Sol-gel techniques were used to make them. PVP polymer was used as a binder to support the backbone frame of the nanofibers. We have characterized our synthesized material to examine its structural, morphological, and electrical properties. XRD of synthesized material tells us about the rhombohedral structure of the R3m space group symmetry. FTIR spectroscopy was used to study the functional groups and vibrations in synthesized material. SEM results confirmed the formation of nanoparticles embedded in nanofibers. In AC analysis, we have discussed dielectric constant, tangent loss, and AC conductivity. The electrical properties of synthesized LiCo_1-xZn_xO₂ (x=0.0, 0.1) nanofibers were studied in a frequency range of 100Hz to 3MHz and found that AC conductivity is high of nanoparticles embedded nanofibers of LiCo_0.9Zn_0.1O₂ i.e., 4.2 x10^-5 (S/m) that plays a crucial role for the supercapacitors and as a cathode material in Lithium-ion batteries(LIBs).

Abstract: Various filling fractions of silver silica nanocomposites (Ag-SiO₂ NC) were successfully synthesized via sol-gel technique and deposited onto indium tin oxide via electrophoretic deposition (EPD). Ag-SiO₂ NC was investigated using X-ray diffraction, FTIR spectroscopy, Uv-vis and transmission electron microscopy. The XRD and Uv-vis results revealed that Ag-SiO₂ NC is stable with a filling fraction of 0.6 in the dielectric medium with excellent absorption peak. Spectroscopy Ellipsometry shows that the effective permittivity and refractive index obtained from this filling fraction are -0.88 and 0.90, respectively. We discovered a ragged of metamaterial properties at negative permittivity.

Abstract: Li₄Ti₅O₁₂ (lithium titanium oxide) or LTO is extensively utilized as active material in Li-ion battery anode mainly due to its zero strain properties and excellent lithium-ion intercalation/deintercalation reversibility with negligible volumetric change. However, LTO is still faced with low electronic conductivity problem, thus the addition of another material such as graphene is necessary to overcome. In this study, LTO was synthesized using sol-gel method with addition of Li varied from 35, 40 and 55 wt% which was controlled by addition of Li₂CO_3. XRD analysis was performed to investigate the crystal structure and phase characteristic of synthesized powder. The results revealed that LTO with addition of 55 wt% Li exhibited the highest purity of Li₄Ti₅O₁₂ phase of 97.7%. It was then added with 5 wt% of graphene. Two-coin cells of Li-ion batteries were made from LTO powders without and with graphene addition as active materials for anode and their electrochemical performances were analyzed. LTO without and with graphene show conductivity of 3.40710^-5 and 2.48810^-5 S/cm, while obtained specific capacity was about 140 mAH and 85 mAh, respectively. This would require further optimization for current experimental condition particularly on graphene addition.