Development of Modified Glasses by Transparent, Functional Hybrid Sol-Gel Nano-Ceramic Coatings, a Comparative Study

This paper concentrates on the development of glasses with self-cleaning surfaces exhibiting high water contact angles. In this study, we prepared super-hydrophobic nano-ceramic coated glass based on titania & silica using simple sol-gel & dip coating methods and studied the best composition of the coatings by altering ratios of titanium tetraisopropoxide (TTIP)/tetraethyl orthosilicate (TEOS) with different homogenizing agents. We characterized the coatings by surface roughness measurement, percentage of optical transmission, static contact angle, near-infrared (NIR) transmission, and diffuse reflectance. The fabrication of coatings on glass substrates played an important role in increasing the water contact angle of about 95° and visible & NIR transmission of about 90%. We compared our modified glass substrate with commercial low emissivity (Low E) glass using X-ray diffraction (XRD) analysis, which showed pure amorphous surface claiming excellent wettability and thus the prepared glass substrate could have a variety of applications in different fields.

New insights into the formation of silicon-oxygen layer on lithium metal anode via in situ reaction with tetraethoxysilane

Lithium metal-based secondary batteries are very promising for next generation power battery due to their high energy density.However,lithium anodes suffer from poor electrochemical reversibility in organic electrolytes due to Li dendrites and instability of the solid electrolyte interphase.Recent research demonstrated that the problem can be alleviated via tetraethoxysilane(TEOS)treated lithium metal to form a silicon oxide layer on the lithium surface,however,its reaction mechanism is controversial.Herein,we deeply explore the reaction mechanism between TEOS and Li and propose:Fresh Li can directly react with TEOS even though no lithium hydroxide exists on the lithium surface,and the participation of water will accelerate the reaction process.Moreover,it was found that the silicon oxide layer can promote the uniform deposition of lithium ions by providing lithiophilic nucleation sites,thereby achieving a long cycle life of Li metal batteries.

Effect of Y-Methacryloxypropyltrimethoxysilane (MPS) and Tetraethoxysilane (TEOS) Towards Preparation of Oil Absorbent Foams from Polyvinyl Alcohol (PVA) Reinforced with Microfibrillated Cellulose (MFC)

Increasing usage of foams in various industry sectors had causing serious disposal problems once it reaches the end of its life-cycle.Herein,PVA-MFC foam was prepared by freeze-drying using polyvinyl alcohol(PVA)and microfibrillated cellulose(MFC)as a reinforced material from sugarcane bagasse(SCB).In this study,the PVA-MFC foam was chemically silylated with Y-methacryloxypropyltrimethoxysilane(MPS)and tetraethoxysilane(TEOS).The wetting ability and mechanical strength of the silylated_(2,20)PVA-MFC foam was greatly enhanced compared with unmodified_(2,20)PVA-MFC foam.The silane chemicals(MPS and TEOS)had been confirmed grafted on_(2,20)PVA-MFC foam due to the presence of Si-C and Si-O-C stretching vibration as showed in Fourier Transform Infrared(FTIR)spectra and cloud-like coating of porous pore was observed in scanning electron microscopy(SEM)images.The silylated_(2,20)PVA-MFC foam(MPS and TEOS)exhibited a series of desirable properties such as lower swelling ratio and high absorption capacity of solvents and oils but had low thermal stability in thermogravimetric(TGA)analysis.The characterization of_(2,20)PVA-MFC foam using TEOS was further investigated.A significant difference in morphology was clearly observed between the unmodified and silylated_(2,20)PVA-MFC-TEOS foam through field emission scanning electron microscopy(FESEM)images.The X-ray photoelectron(XPS)analysis of silylated_(2,20)PVA-MFC-TEOS foam confirmed the presence of C,O and trace amount of Si elements.These synthesized_(2,20)PVA-MFC foam could be a promising material for broad range of polymer foam applications.

A study of Corrosion Protection of Aluminum Metal by Tetraethoxysilane Plasma Polymerized Coatings -Influence of Aluminum Surface Pretreatments-

The corrosion-protective performance of plasma-polymerized (PP) coatings on pretreated aluminum substrates has been investigated by cathodic polarization curve measurement. The surface composition and electronic properties of the pretreated and PP film coated metal surfaces were also characterized by XPS and the temperature-programmed photoelectron emission (TPPE). A PP coating was prepared on the pretreated surfaces by plasma polymerization of a mixture of tetraethoxysilane (TEOS) monomer vapor and oxygen using a 13.56MHz radiofrequency generator. The polarization curve of PP film coated samples was measured in NaCl aqueous solution. The weight loss rate calculated from the value of the corrosion current of the curve was used to estimate the protective performance of the PP film coated samples. Argon plasma treatment of the metal surface gave much better corrosion-protective performance than pretreatments such as oxidation by heating in air and diamond scratching. The XPS analysis indicated that the silicon oxide assigned to SiO2 was formed on the PP film coated surface. The TPPE analysis revealed that the electron emission characteristics for the metal surfaces pretreated only were strongly influenced by the pretreatments, while all the PP film coated samples exhibited nearly the same electron emission trend with a much decreased intensity.

Investigation of UV photosensor properties of Al-doped SnO_(2) thin films deposited by sol-gel dip-coating method

Transparent conducting aluminum doped tin oxide thin films were prepared by sol-gel dip coating method with differ-ent Al concentrations and characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), UV-Vis spectrophotometry and photoconductivity study. The variation observed in the properties of the measured films agrees with a difference in the film's thickness, which decreases when Al concentration augments. X-ray diffraction analysis reveals that all films are polycrystal-line with tetragonal structure, (110) plane being the strongest diffraction peak. The crystallite size calculated by the Debye Scher-rer’s formula decreases from 11.92 to 8.54 nm when Al concentration increases from 0 to 5 wt.%. AFM images showed grains uni-formly distributed in the deposited films. An average transmittance greater than 80% was measured for the films and an en-ergy gap value of about 3.9 eV was deduced from the optical analysis. Finally, the photosensitivity properties like current-voltage characteristics, ION/IOFF ratio, growth and decay time are studied and reported. Also, we have calculated the trap depth energy using the decay portion of the rise and decay curve photocurrent.

Structural evolution-enabled BiFeO3 modulated by strontium doping with enhanced dielectric,optical and superparamagnetic properties by a modified sol-gel method

Multiferroic(BFO)nanoparticles doped with strontium with the general formula Bi1-xSrx FeO3(x=0,0.3,0.5,0.7)were synthesized using a modified sol-gel auto-combustion process.The structural,electrical,optical,and magnetic properties of the samples are discussed.The structural analysis,carried out using the x-ray powder diffraction technique,shows a structural transition from rhombohedral(R-3c)to cubic(Pm-3m)for the doping amount of strontium(Sr)equal to x=0.3.Morphological analysis of the prepared samples were carried out using scanning electron microscopy(SEM).Frequency-dependent dielectric constant and ac conductivity were studied.The doped samples,with improved dielectric properties,can be used to fabricate different optoelectronic devices.Strong dielectric dispersion and broad relaxation were exhibited by all the samples.Cole–Cole plots were employed as an effective tool to study the dispersion parameters,namely,the optical dielectric constant,static dielectric constant,relaxation time,and spreading factor.The activation energy was calculated from the relaxation peaks and Cole–Cole plots,which were found to be compatible with each other.The bandgap of the samples was calculated using diffuse reflectance spectral(DRS)analysis.Sharp and strong photoluminescence in the IR region was observed in the samples,similar to ZnO,which was reported for the first time.Room-temperature and low-temperature magnetization studies point towards the superparamagnetic nature of the samples,with an improvement in magnetic properties with doping.The antiferromagnetic behavior of bulk bismuth ferrite transforms to superparamagnetic in nature for both pure and Sr-substituted bismuth ferrite nanoparticles due to the close dimensions of crystallite size with magnetic domains leading to the break-down of the frustrated spin cycloidal moment.

Comparative structural and electrochemical properties of mixed P2/O′3-layered sodium nickel manganese oxide prepared by sol-gel and electrospinning methods:Effect of Na-excess content

The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X-ray diffraction results of the prepared NNMO without adding Na-excess content indicate sodium loss,while the mixed phase of P2/O′3-type layered NNMO presented after adding Na-excess content.Compared with the sol-gel method,the secondary phase of NiO is more suppressed by using the electrospinning method,which is further confirmed by field emission scanning electron microscope images.N_(2) adsorption-desorption isotherms show no remarkably difference in specific surface areas between different preparation methods and Na-excess contents.The analysis of X-ray absorption near edge structure indicates that the oxidation states of Ni and Mn are+2 and+4,respectively.For the electrochemical properties,superior electrochemical performance is observed in the NNMO electrode with a low Na-excess content of 5wt%.The highest specific capacitance is 36.07 F·g^(-1)at0.1 A·g^(-1)in the NNMO electrode prepared by using the sol-gel method.By contrast,the NNMO electrode prepared using the electrospinning method with decreased Na-excess content shows excellent cycling stability of 100%after charge-discharge measurements for 300 cycles.Therefore,controlling the Na excess in the precursor together with the preparation method is important for improving the electrochemical performance of Na-based electrode materials in supercapacitors.

Preparation of long alumina fibers by sol-gel method using tartaric acid

Long alumina fibers were prepared by sol-gel method.The spinning sol was obtained by mixing aluminum nitrate,tartaric acid,and polyvinylpyrrolidone with a mass ratio of 10∶3∶1.5.Thermogravimetry-differential scanning calorimetry （TG-DSC）,Fourier transform infrared （FT-IR） spectra,X-ray diffraction （XRD）,and scanning electron microscopy （SEM） were used to characterize the properties of the gel and ceramic fibers.A little of α-Al2O3 phase is observed in the alumina precursor gel fibers sintered at 1273 K.The fibers with a uniform diameter can be obtained when sintered at 1473 K,and its main phase is also indentified as α-Al2O3.

Preparation and optical characteristics of ZnO films by chelating sol-gel method

The effect of different annealing temperatures on the structure, morphology,and optical properties of ZnO thin films prepared by the chelating sol-gel method was investigated.Zinc-oxide thin films were coated on quartz glass substrates by dip coating. Zinc nitrate, absoluteethanol, and citric acid were used as precursor, solvent, and chelating agent, respectively. Theresults show that ZnO films derived from zinc-citrate have lower crystallization temperature (below400℃), and that the crystal structure is wurtzite. The films, treated over 500℃, consist ofnano-particles and show to be porous at 600℃. The particle size of the film increases with theincrease of the annealing temperature. The largest particle size is 60 nm at 600℃. The opticaltransmittances related to the annealing temperatures become 90% higher in the visible range. Thefilm shows a starting absorption at 380 nm, and the optical band-gap of the thin film (fired at500℃) is 3.25 eV and close to the intrinsic band-gap of ZnO (3.2 eV).

Effect of surfactants on the structure and photoelectric properties of ITO films by sol-gel method

The Indium tin oxide（ITO） thin film possesses excellent photoelectric properties that enable it to act as an ideal transparent conductor.To obtain high-quality ITO films through sol-gel method, the ionic surfactant monoethanolamine and the non-ionic surfactant polyethylene glycol（PEG） were added to the ITO precursor slurry.The influences of surfactants on the structural and photoelectric properties of ITO film samples were investigated.XRD patterns indicated that surfactant monoethanolamine contributed to film predominant grain orientation along the（400） plane.The high transmittance（over 95%） was attributed to the preferred orientation and the grain size expansion of ITO films.SEM showed that the surface particle size and the morphology of ITO films were strongly dependent on the kind of surfactants used.Moving to the shortwave region, the absorption edge of the films exhibited the Burstein-Moss shift.

Preparation of Perovskite-Type Oxides La_(1-x)Sr_xFe_(1-y)Co_yO_3 Using EDTA Sol-Gel Method

Two series of perovskite-type oxides with composition (La_(1-x))Sr_xFeO_3(x≤0.8)and La_(1-x)Sr_xFe_(1-y)Co_yO_3(x=0.2; y=0.2, 0.4)powder productions were synthesized by EDTA complexing sol-gel method. The products were characterized by XRD, TEM, SEM, BET method(N_2 adsorption)and laser granularity analysis for different synthesis conditions to obtain the optimum conditions for the preparation process. Single-phased, uniform perovskite-type oxides with small particle size were obtained by EDTA sol-gel process with high stability and repeatability, and the process temperature is much lower than that of solid state reaction method.

Preparation and Characterization of Pb(Zr_(0.52)Ti_ (0.48))O_3 Ultrafine Powders by a Sol-gel Combined with Combustion Process

A simple and rapid process for synthesizing lead zirconate titanate,Pb（Zr0.52Ti0.48）O3（PZT）,ferroclectric powders was developed.This process,combining the sol-gel and combustion process.offers several advantages over conventional methods.including rapid solution synthesis,use of commercially available materials lower synthesis temperature and ease of obtaining ultrafine powders.The precursor solution for synthesizing powders was prepared from lead nitrate.zireonium nitrate.titanium oxynitrate,citric acid and deionized water.The precarsor was investigated by DSC-TG,and the PZT powders were investigated by powder-XRD,IR spectra and TEM.XRD analysis shous that the powders possess a single phase perovskite type structure,no pyrochlore phase exists.and TEM image shows that the grain size of the powders is about 40nm.

Infrared Thermochromic Properties of VO_2 Thin Films Prepared through Aqueous Sol-gel Process

The stoichiometric vanadium（IV） oxide thin films were obtained by controlling the temperature, time and pressure of annealing. The thermochromic phase transition and the IR thermochromic property of 400 nm and 900 nm VO2 thin films in the 7.5 μm-14 μm region were discussed. The derived VO2 thin film samples were characterized by Raman, XRD, XPS, AFM, SEM, and DSC. The resistance and infrared emissivity of VO2 thin films under different temperature were measured, and the thermal images of films were obtained using infrared imager. The results show that the VO2 thin film annealed at 550 ℃ for 10 hours through aqueous sol-gel process is pure and uniform. The 900 nm VO2 thin film exhibits better IR thermochromic property than the 400 nm VO2 thin film. The resistance of 900 nm VO2 film can change by 4 orders of magnitude and the emissivity can change by 0.6 during the phase transition, suggesting the outstanding IR thermochromic property. The derived VO2 thin film can control its infrared radiation intensity and lower its apparent temperature actively when the real temperature increases, which may be applied in the field of energy saving, thermal control and camouflage.

Intense up-conversion emissions of yb3＋/Dy3＋ co-doped A12O3 nanopowders prepared by non-aqueous sol-gel method＊

yb3＋/Dy3＋ co-doped A1203 nanopowders have been prepared by the non-aqueous sol-gel method and their up- conversion photoluminescence spectra are measured under excitation by a 980-nm semiconductor laser. The results show that there are comparatively abundant spectra of up-conversion emissions centered at 378, 408, 527 and 543, and 663 nm, corresponding to 4C9/2→ 6H13/2, 4C9/2→ 6Hll/2, 4115/2 → 6H13/2, and 4F9/2 →6Hll/2 transitions of Dy3＋, respectively. Two-photon and three-photon processes are involved in ultraviolet, violet, green, and red up-conversion emissions. The energy transition between Yb3＋ and Dy3＋ is discussed.

Fe^(3+)-Doped Anatase TiO_2 Study Prepared by New Sol-Gel Precursors

FeTi_1-O_2（= 0.00,0.05,0.10） nanocomposites are synthesized using a sol-gel method involving an ethanol solvent in the presence of ethylene glycol as the stabilizer,and acetic acid as the chemical reagent.Their structural and optical analyses are studied to reveal their physicochemical properties.Using the x-ray diffractometer（XRD）analysis,the size of the nanoparticles（NPs） is found to be 18-32 nm,where the size of the NPs decreases down to 18 nm when Fe impurity of up to 10% is added,whereas their structure remains unchanged.The results also indicate that the structure of the NPs is tetragonal in the anatase phase.The Fourier transform infrared spectroscopy analysis suggests the presence of a vibration bond（Ti-O） in the sample.The photoluminescence analysis indicates that the diffusion of Fe^（3＋） ions into the TiO_2 matrix results in a decreasing electron-hole recombination,and increases the photocatalytic properties,where the best efficiency appears at an impurity of10%.The UV-diffuse reflection spectroscopy analysis indicates that with the elevation of iron impurity,the band gap value decreases from 3.47 eV for the pure sample to 2.95 eV for the 10 mol% Fe-doped TiO_2 NPs.

Enhancement of Active Anticorrosion via Ce-doped Zn-Al Layered Double Hydroxides Embedded in Sol-Gel Coatings on Aluminum Alloy

Ce-doped Zn-Al layered double hydroxide（LDH） nanocontainer was synthesized by a co-precipitation method. X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FT-IR）, scanning electron microscopy（SEM） and transmission electron microscopy（TEM） methods were used for the characterization of the LDH nanocontainer. The anticorrosion activity of the LDH powders embedded in a hybrid sol-gel coating on aluminum alloy 2024 was investigated by electrochemical impendence spectroscopy（EIS）. The results showed that Ce（III） ions were successfully incorporated into LDHs layers. The sol-gel coating modified with Ce-doped Zn-Al LDHs exhibited higher anticorrosion behavior compared with both unmodified and Ce-undoped LDHs containing coatings, which proved the applicability of Ce-doped LDHs in delaying coating degradation and their potential application as nanocontainers of corrosion inhibitors in self-healing coatings.

Structural, Optical and Luminescence Properties of ZnO Thin Films Prepared by Sol-Gel Spin-Coating Method： Effect of Precursor Concentration

Transparent zinc oxide（ZnO） thin films are fabricated by a simple sol-gel spin-coating technique on glass substrates with different solution concentrations（0.3-1.2 M） using zinc acetate dehydrate [Zn（CH_3COO）_2·2H_2O] as precursor and isopropanol and monoethanolamine（MEA） as solvent and stabilizer, respectively. The molar ratio of zinc acetate dehydrate to MEA is 1.0. X-ray diffraction, ultraviolet-visible spectroscopy and photoluminescence spectroscopy are employed to investigate the effect of solution concentration on the structural and optical properties of the ZnO thin films. The obtained results of all thin films are discussed in detail and are compared with other experimental data.

Synthesis of Anatase TiO_2 Nanoparticles by Improved Sol-Gel Process at Low Temperature

The nanocrystalline TiO_2 powder were prepared by improved sol-gel method at low temperature under ambient pressure. The prepared TiO_2 powder was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM). It is found that the yield of anatase TiO_2 significantly increases with the reduction of pH by increasing the nucleation rate of anatase. There is an optimum amount of water in sol for the formation of anatase by combining two effects on the concentration of Ti(OH)_4 in gels. Increasing in reaction temperature also benefit to the nucleation of anatase of TiO_2.

Initial Study of Strontium Barium Niobate/Strontium Barium Titanium Ceramics through A Modified Sol-Gel

Barium strontium titanate niobate (BSTN) composite ceramics system following the general formula 0.5BaO·0.5SrO·0.5TiO2·0.5Nb2O6 was successfully prepared. The investigation is carried out through a modified sol-gel method. By controlling the viscosity of the sol solution to suspend the strontium barium niobate ceramic powder uniformly which had been made beforehand and the viscosity of the sol could be changed by adjusting the mixture ratio of the precursor. Powders obtained from dried gels were calcined at 800 ℃ for 3 h. The bulk ceramics obtained from the dried powders were sintered at the temperatures of 1250 and 1300 ℃ respectively. The results of the XRD and SEM indicated that the perovskite phase and the tungsten bronze phase could be coexisted stably in BSTN at both of these temperatures. The increasing of the sintering temperature was good for the crystal phase growing and the solubility of the two phases in the composite ceramics. And the theory of adulteration could be adopted to resolve the phenomena that sintering temperatures too high, which resulted in the crystalline grains growing singularly. Some problems were put forward to pay attention to this material research process.

Preparation of Y_2O_3 Nanopowders by Sol-Gel Method

Using the inexpensive inorganic salts as the starting materials,pure yttria nanopowders were prepared by sol-gel method. The primary particles are spherical and about 60 nm in diameter with a narrow size distribution. Moderate sulfate ions used as additive were the key to the formation of precursor and the preparation of spherical Y_2O_3 nanopowders. Transformation of the precursor was investigated during the calcining. The influence of calcination temperature on size and purity of production was analyzed. The results show that higher temperature is beneficial to the preparation of pure and complete crystallization of yttria powders under the condition of not making particles excessively grow.