Papers by Keyword: Sol-Gel Process

Abstract: Bioactive glasses based on the SrBGs: 45SiO2 - 6P2O5 - 15SrO - 34CaO, 5Zn-SrBGs (wt.%): 45SiO2 - 6P2O5 - 15SrO - 29CaO - 5ZnO (wt.%), and 5Ce-SrBGs: 45SiO2 - 6P2O5 - 15SrO - 29CaO – 5CeO (wt.%) were successfully synthesised through the sol-gel process under the acid condition. The concentration of nitric acid at 0.01M was an optimal condition to accelerate the hydrolysis and polycondensation reactions in these systems. SEM images showed the primary particle nucleus growth in the morphological structure of the SrBGs, 5Zn-SrBGs, and 5Ce-SrBGs. FTIR spectra indicated the incorporation of therapeutic cations in the glass structure whilst maintaining the morphological structure. XRD and SEM suggested the crystalline apatite formation on the surface of BGs after the BGs were incubated in the simulated body fluid (SBF) at pH 7.4 for 21 days. EDS-SEM indicated the apatite formation whilst containing doping ions in the glass structure. All three BGs formulations could promote the murine pre-osteoblast cell (MC3T3-E1) cell proliferation at the concentration between 200-250 µg/mL and have no in vitro cytotoxicity on MC3T3-E1 cells up to the concentration of 1mg/mL.

Abstract: Renewable energy source is a clean energy production source and can overcome climatic challenges caused by the excessive use of fossil fuels. The nanocrystalline material of composition Cu_0.2Fe_0.2(Ce_0.6Gd_0.4-xNd_x)_0.6O_2-x has been synthesized by WOWS sol-gel process by varying Neodymium as such x= 0.0, 0.05. These samples were calcined at 500°C for 2 hours and the pellets were sintered at 750°C for 5 hours. X-Ray Diffraction technique confirms the cubic fluorite structure of the material. The doped material has showed high dielectric constant value and low dissipation factor and increased AC conductivity. AC conductivity obeys the Universal Dielectric Response. The material shows the potential for applications such as an electrode/electrolyte for fuel cells or also as a dielectric resonator.

Abstract: Ba_0.85Ca_0.15Ti_0.9Zr_0.1O₃ (BCTZ) ceramics, one of the lead-free pizoelectric materials, were focused due to the environmental concern against lead. A modified BCTZ powder sol-gel fabrication process was experimentally introduced with the addition of glycerol, in order to provide an effective approach to optimize the piezoelectric response of BCTZ ceramics. The results showed that the piezoelectric properties enhanced in terms of the piezoelectric coefficient of d₃₃, 510 pC/N and the electromechanical coupling coefficient of k_p, 0.501. The enhancement in electrical properties, such as dielectric, ferroelectric and piezoelectric, could be related to the homogenous microstructure and larger grain size of BCTZ ceramic powders after the introduction of glycerol during the modified sol-gel strategy.

Abstract: The Pseudoboehmite is an aluminum compound used as an alumina precursor and it is produced by sol-gel process. The sol-gel process is a methodology to produce porous, vitreous or crystalline ceramics started by molecular precursors. Pseudoboehmite with high purity, high specific surface area and porous homogeneity was obtained by sol-gel process. The material was used to produce gamma-alumina with surface area ranging from 211.2-288.1m²/g. It was studied the effect of aging time, temperature of aging and poly (vinyl alcohol) addition in the synthesis.

Abstract: The objective of this project was to develop the hydrophobic film for self-cleaning glasses. The effects of octyltriethoxysilane (OTES) additions to hydrolysis of tetraethylorthosilicate (TEOS) on hydrophobic and optically transparent properties were studied. The film was prepared by sol-gel method from the precursors namely, TESO, OTES, isopropanol alcohol (IPA), and deionized water (DI). The sols for coating were obtained with TEOS/OTES ratio of 50:50 to 99:1. The sols were deposited on a commercial glass and dried at 60oC for an hour. After drying, the film properties were characterized by fourier transform infrared spectroscopy (FTIR), UV-VIS Spectrophotometer, x-Ray Diffractometer (XRD), atomic force microscope (AFM), optical microscopy and contact angle meter. It was found that contact angles of the hybrid films increased with the OTES addition, reaching a maximum at 10 wt.%, and the contact angle values were the same as for further addition. The light transmittance was rather stable with increasing amounts of OTES. For the optimized condition, the water contact angle of 108o and light transmittance of 91%, was obtained with TEOS/OTES ratio of 90:10.

Abstract: This work aims to study the effect of SiO₂ and heat treatment temperature in TEOS-SiO₂-OTES film on the hydrophobic property and weathering durability. TEOS-SiO₂-OTES film was prepared by sol-gel process. Tetraethylorthosilicte (TEOS) and Octyltriethoxysilane (OTES) were used to form the gel. The contents of SiO₂ were varied at 0.5% 1% 3% 5% and 10% by weight. The film was deposited on a glass slide by spin coating. The hydrophobic property was studied by FTIR, UV-VIS spectroscopy, SEM, XRD and contact angle. The weathering chamber was used for studying weathering durability. The weathering condition was controlled at 50 oC and 85%RH. Moreover, the chemical resistant was also tested. The study showed that the silica contents affected the surface roughness of film. The surface roughness of film decreased with increasing amounts of SiO₂.

Abstract: In this work, the sol-gel method was used to prepare composite gels based on 1,2-bis(5-triethoxysilyl-3-thiopentoxy)ethane and tetraethoxysilane, which showed sorption properties for strontium cations. Composite gels with colloidal silica were obtained. The obtained gels possess sorption activity to strontium cations. Template synthesis of gels in the presence of cesium cations was carried out. The results of sorption demonstrate the expected manifestation of the template effect, which determines the selectivity to cesium cations.

Abstract: Using samarium (III) nitrate hexahydrate, manganese nitrate and citric acid as main raw materials, the SmMnO₃ gel was prepared by sol-gel process. The gel was kept at 100 °C for 24 h to get the xerogel. Then, the xerogel was respectively calcined in muffle furnace at 600 °C, 700 °C, 800 °C and 900 °C. The structure and morphology of samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier Transform Infrared (FT-IR) spectroscopy. The UV photocatalytic activities of SmMnO₃ were investigated by methyl orange which was used as simulated sewage. The results show that the pure SmMnO₃ can be obtained through calcination between 700 °C and 800 °C, and the SmMnO₃ have an average particle size of 80 nm. The SmMnO₃ samples calcined at 700 °C and 800 °C show high photocatalytic activity for decomposition of methyl orange under UV-light irradiation. The SmMnO₃ samples are consistent with first-order kinetics for the degradation of methyl orange. And the apparent rate constants are respectively k₇₀₀ =0.01206 min^-1and k₈₀₀=0.01088 min^-1.

Abstract: The development of hard coating based on colloidal silica nanoparticles on polymethyl methacrylate (PMMA) sheet was reported. The colloidal silica was surface-modified with methyltrimethoxysilane (MTMS) and formulated to hard coating solution via sol-gel process. The hard coating solution was applied to PMMA surface by spray deposition technique. Spraying process was carried out from spray nozzle outlet diameter of 0.35 mm and air compress pressure at 0.2 MPa with nozzle to substrate distance at 10 cm. The different coating thicknesses were obtained by adjusting the amount of coating applied. The optimal coating thickness that gives the highest pencil-hardness at 7H and 100% adhesion for adhesion tape test is 10 μm.

Abstract: Pd-doped SiO₂ organic-inorganic membrane materials were prepared via a sol-gel process. The sol stability is characterized by sol particle size and zeta potential analysis. And the properties of the Pd-doped SiO₂ organic-inorganic membrane materials are investigated by X-ray diffraction (XRD), fourier transform infrared (FTIR), energy dispersive spectrum (EDS) analysis and N₂ absorption-adsorption measurement. The results showed that the sol particle size distributions are relatively narrow. With the increase of Pd content, the sol particle sizes slightly increase and the zeta potentials decreases until the palladium/tetraethylorthosilicate molar ratio closes to the isoelectric point. After calcined at 350 °C under H₂ atmosphere, the added PdCl₂ is reduced to metallic Pd⁰ completely, and the hydrophobic Si−CH₃ groups exist in the SiO₂ network. The Pd atoms have a lower concentration on the surface and more Pd atoms embedded in the SiO₂ matrix. The Pd-doped SiO₂ membrane materials calcined at 350 °C with a palladium/tetraethylorthosilicate molar ratio of 0.15 exhibit large BET surface area (up to 683.36 m²/g) and total pore volume (up to 0.386 cm³/g), as well as a mean pore diameter of about 2.26 nm.