Abstract isopropoxide as a precursor and Al2O3

AbstractAl2O3-TiO2composites can be used as thermal-resistant parts, catalysts, wear-resistantcoatings, and lubricative additives, solar cell chemical, marine industries andhumidity sensor. Titania-alumina nanocomposite will be prepared by usingdifferent ratios of  TiO2 andAl2O3 individually prepared by using sol-gel method. TiO2Will be prepared by using Titaium tetra isopropoxide as a precursor andethanol, water as solvents and HCl.Mixture of  water and HCL will be added drop wise in themixture of TTIP and ehtanol.

Al2O3 will be prepared byusimg Aluminium nitrate as the starting material first aluminium nitrate andwater solution is mad and then ethanol will be added dropwise in this solution.TiO2 Will be prepared by using Titaium tetra isopropoxide as aprecursor and Al2O3 will be prepared by usimg Aluminiumnitrate as the starting material and then TiO2-Al2O3composite will be prepared by using mechano-chemical method. The role of aluminacontent on the structural properties, phase transformation, surface area andparticle size of titania will be investigated. The samples willbe characterized by using X-Ray Diffraction (XRD), Scanning Electron Microscopy(SEM) and UV-vis spectroscopy. Introduction        Nanoparticlesand nanostructural materials have been considered an attractive family of materialsover the last decades due to their novel properties that are not present in thebulk.

The unique properties of nanomaterials result from the small sizes andlarge specific surface areas. The design and fabrication of the nanostructuredmaterials have received considerable attention due to their interestingphysical and chemical properties, and their potential applications in industryand technology. Nanocrystalline titanium dioxide has a widespread range of newapplications as important material in photocatalyst, solar cell, chemical, marineindustries and humidity sensor (Ahmed and Abdel-Messih, 2011).

Al2O3-TiO2composites can be used as thermal-resistant parts, catalysts, wear-resistantcoatings, and lubricative additives. However, homogeneous distribution of theconstituents Al2O3 and TiO2 remains a big challengeto fabricate composites of high performance. There have been immense efforts toprepare Al2O3/TiO2 mixtures, among which sol-gelmethod offers great advantages of low-cost, molecular-scale mixing andfeasibility of composition and structure control (Yang et al.,2015).

Al2O3-TiO2nanocomposites prepared by sol-gel method to obtain highly dispersed and smallparticle sizes of Al2O3. Highly ordered mesoporous Al2O3-TiO2was employed for solar cells applications and highly efficient photocatalyst.Nonmetalic elements and metalic elements such as Ru, Si, and Te were doped TiO2/Al2O3composite films for environmental applications. TiO2-Al2O3 nanocomposites eithermembrane or film were employed for photodegradation of different pollutantssuch as dyes.

All the prepared TiO2-Al2O3nanocomposites photocatalysts exhibited their the superiority as efficientphotocatalysts more than pure TiO2 (Ismail et al.,2015). Improving the antimicrobialactivity and radical scavenging ability of a textile-based nanocomposite is thekey issue in developing a good and flexible wound dressing. In thiswork,flexible textile attached with Al2O3-TiO2nanoparticles was prepared by dipping the textile in a suspension containing Al2O3-TiO2nanoparticles. Increased antimicrobial activity measured by optical density at600 nm recorded for textile/Al2O3-TiO2 bimetaloxide nanocomposites showed better interaction between Al2O3and TiO2 nanoparticles (Parham et al.,2016).Aims and objectiveInthe present research work, TiO2-Al2O3 compositewill be prepared by using sol-gel technique using different ratios of  TiO2 and Al2O3.Then these samples will be characterized by using X-Ray Diffraction (XRD), ScanningElectron Microscoy (SEM) and UV-vis spectroscopy.

Review  of LiteratureAlot of work has been done on composite of TiO2-Al2O3.Preparation of TiO2-Al2O3 by using differenttechniques had been discussed by many researchers. TiO2-Al2O3structures are used in various applications including catalysis, solar cells,photocatalytic, and self-cleaning.

TiO2-Al2O3nano-composites can also be used as thermal resistant materials due to theirexcellent thermal expansion.Anunagglomerated, monosized A12O3-TiO2 compositepowder was prepared by the stepwise hydrolysis of titanium alkoxide in an A12O3dispersion. Particle size was controlled by selecting the particle size of thestarting A12O3 powder TiO2 content wasdetermined by the amount of alkoxide hydrolyzed. A composite-powder compactcontaining 50 mol% TiO2, when fired at 1350°C for 30 min, showed nearlytheoretical density with aluminum titanate phase formation. Al2O3-TiO2compositepowder can be sintered to form either an aluminum titanate or a rutile corundumcomposite ceramic by controling the sintering conditions (Okamura et al.,1986). TiO2 particles heatingsuch powders in air shows that structural behaviour is influenced by the micromorphology of thecomposite particle.

Transformation temperatures of  the  titania phases seem to depend upon some size parameter which would representtheir  morphology within  the powders. Studies performed on a series of non-equimolar Al2O3-TiO2composite powders showed that the temperature of ?-Al2O3formation may be decreased by ~210 °C possibly due to  a seeding effect of rutile. Pseudobrookite Al2TiO5was never detected at ? 1300 °C in air.

Transformations  of the  titania  phases are  not always  observable in  DTA  whereas they  are  readily seen from  a  posteriori recorded  X-ray  diffraction patterns (Brugger et al.,1986). Catalyst support materials basedupon composite metal oxides often incorporate the beneficial aspects of theconstituents. For the case of TiO2-Al2O3composites, however, it has proven difficult to retain a high anatase contentand surface area at temperatures of 900 °C and above. This work reports asol-gel synthesis method that solves these problems.

The action of acetic acidin the preparation mixture during sol formation and calcination, augmented bysolid solution formation between TiO2 and Al2O3during calcinations, seems to account for these results (Subramanian etal., 2006).Inthe present research, self-cleaning Al2O3-TiO2thin films were successfully prepared on glass substrate using a sol–geltechnique for photocatalytic applications. We investigated the phase structure,microstructure, adhesion and optical properties of the coatings by using XRD,SEM, scratch tester and UV/Vis spectrophotometer. Four different solutions wereprepared by changing Al/Ti molar ratios such as 0, 0.

07, 0.18 and 0.73. Glasssubstrates were coated by solutions of Ti-alkoxide, Al-chloride, glacial aceticacid and isopropanol. The obtained gel films were dried at 300 °C for 10 minand subsequently heat-treated at 500 °C for 5min in air. The oxide thin filmswere annealed at 600 °C for 60 min in air. TiO2, Ti3O5,TiO, TiO2, ?-Al2O3 and AlTi phases weredetermined in the coatings. The microstructural observations demonstrated thatAl2O3 content improved surface morphology of the filmsand the thickness of film and surface defects increased in accordance withnumber of dipping.

It was found that the critical load values of the films with0, 0.07, 0.18 and 0.73 Al/Ti molar ratios were found to be 11, 15, 22 and 28mN, respectively. For the optical property, the absorption band of synthesizedpowders shifted from the UV region to the visible region according to theincrease of the amount of Al dopant. The oxide films were found to be activefor photocatalytic decomposition of methylene blue (Celik et al.,2007).

Al2O3-TiO2nanocrystalline powders were synthesized by sol–gel process. Aluminumsec-butoxide and titanium isopropoxide chemicals were used as precursors andethyl acetoacetate was used as chelating agent. Thermal and crystallizationbehaviors of the precursor powders were investigated by thermalgravimetric-differential thermal analysis, Fourier-transform infrared spectrumand X-ray diffraction. The average crystalline size of heat treated Al2O3-TiO2powders at 1100 °C is ~100 nm. Energy dispersive x-ray EDX line scan analysisindicates that the Al2O3 and TiO2 phases arehomogeneously distributed in the Al2O3-13 wt% TiO2nanocrystalline powders (Chen and Jordan, 2009).NanostructuredAl2O3-TiO2 composite films were prepared onglass substrates by metalorganic chemical vapor deposition (MOCVD) usingaluminum acetylacetonate and titanium tetraisopropoxide precursors.Oxygen andargon were used as the reactive and carrier gases, respectively. Depositiontemperature (Tdep) was varied from 723 to 873 K and total pressure was keptconstant at 133–266 Pa.

The formation of composite films was achieved by mixingthe precursor vapors, which were obtained by heating the aluminum and titaniumprecursors at 403 and 323-353 K, respectively. The films were characterized byXRD, SEM and TEM. The crystalline structure and the surface morphology of thenanostructured Al2O3-TiO2 composite films werestrongly dependent on the precursor and deposition temperatures (Pérez et al., 2010). Highly orderedmesoporous Al2O3/TiO2 was prepared by sol-gelreaction and evaporation-induced self-assembly (EISA) for use in dye-sensitizedsolar cells.

The prepared materials had two-dimensional, hexagonal porestructures with anatase crystalline phases. The average pore size of mesoporousAl2O3/TiO2 remained uniform and in the rangeof 6.33-6.

58 nm. The thin Al2O3 layer was located mostlyon the mesopore surface, as confirmed by X-ray photoelectron spectroscopy(XPS). The Al2O3 coating on the mesoporous TiO2film contributes to the essential energy barrier which blocks the chargerecombination process in dye-sensitized solar cells.

The resultant materials Al2O3/TiO2with a highly ordered mesoporous structure to DSSC and conformed the thin Al2O3layer improved both the pore structure and photovoltaic characteristics (Kim et al.,2010). Composite fibers of TiO2-Al2O3were prepared by electrospinning a sol–gel and polymer mixture to formtemplate polymeric fibers followed by calcination. The resulting fibers werecharacterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD),diffuse reflectance ultraviolet–visible (UV-vis) spectroscopy, scanningelectron microscopy (SEM), transmission electron microscopy (TEM), X-ray energydispersive spectroscopy (XEDS), and X-ray photoelectron spectroscopy (XPS).Calcination at 973 K resulted in mixture of anatase (A) titania and gamma (?)alumina phases. We calculated a band gap energy of 3.3 eV and found the averagediameter of the resulting fibers in the 150-400 nm range.

Both XEDS and XPSreveal that fibers are predominantly made of titania (Lotus et al.,2010).  Al2O3-xTiO2composite coatings were deposited onto mild steel substrates by atmosphericplasma spraying of mixed micron-sized Al2O3 andnano-sized TiO2 powders.Phase transformation from mainly stable ?-Al2O3and anatase-TiO2 in the powders to predominant metastable ?-Al2O3and rutile-TiO2 in the coatings was observed. Hardness wasfound to decrease with increasing TiO2 content while fracture toughnessincreased. The average wear rates of composite coatings determined by slidingwear test were lower than that of monolithic Al2O3 coatingby approximately 40% (Dejang et al.

,2010). Nitrogen doping TiO2and ?-Al2O3 composite oxide granules (N-TiO2/?-Al2O3)were prepared by co-precipitation/oil-drop/calcination in gaseous NH3process using titanium sulphate and aluminum nitrate as raw materials. Aftercalcination at 550 °C in NH3 atmosphere, the composite granules showedanatase TiO2 and ?-Al2O3 phases with thegranularity of 0.5-1.0 mm. The anatase crystallite size of composite granuleswas range from 3.5?25nm calculated from XRD result.

The product granules could be used as aphotocatalyst in moving bed reactor, and was demonstrated a highervisible-light photocatalytic activity for 2,4-dichlorophenol degradationcompared with commercial TiO2. The high visible-light photocatalyticactivity might be a synergetic effect of nitrogen doping and the form of binarymetal oxide of TiO2 and ?-Al2O3 (Huang et al.,2013). The polymer polyvinylidenefluoride (PVDF) membranes were modified by blending with nanometer particles toimprove its hydrophilic property and anti-fouling performances in the processof waste water treatment. The organic macromolecule composite ultrafiltration(UF) membranes modified by the inorganic nanometer TiO2 and Al2O3were prepared by a phase inversion process. The composite membranesperformances, such as water flux, mechanical strength, water contact angle,retention rate, pores size and pores size distribution, were compared to thoseof organic membranes. The surface and sectional structures of membranes wereobserved by scanning electron microscope (Hong et al.,2013).

Inthis work, TiO2-Al2O3 nano-composite filmswere deposited on glass substrates by the sol gel method. The structural andoptical properties of TiO2-Al2O3 nanocompositefilms were characterized for different Al2O3:TiO2volume ratio in TiO2-Al2O3 solution. Thecrystal size of TiO2 nanoparticles in TiO2-Al2O3nanocomposite films was determined for the different Al2O3:TiO2volume ratios. Band gap energy values of the films were controlled by changingAl2O3:TiO2 ratios. The properties of TiO2-Al2O3nano-composite films were characterized by X-ray diffraction (XRD), atomic forcemicroscopy (AFM), ultraviolet–visible spectroscopy (UV-vis), scanning electronmicroscopy (SEM), spectrophotometer (Perkin Elmer), and Fourier transforminfrared spectroscopy (FTIR). SEM results showed flower-like TiO2-Al2O3nano-composite films (Akkaya Arier and Tepehan, 2014). Titaniumdioxide (TiO2) is usually introduced into dielectric layer ofaluminum electrolytic capacitor to enhance capacitance performance via formingAl2O3-TiO2composite film. However, there is abig obstacle caused by high crystallization temperature of TiO2 tocapacitance enhancement.

In present work, a facile route was proposed tosynthesize crystalline TiO2 with the size of 3-10 nm at room temperatureusing lactic acid (LA) and acetylacetone (Acac) as double chelators. Afterbeing introduced into the surface of etched aluminum foils as dielectric layer,TiO2 boosted the specific capacitance by about 24% compared to thatwithout TiO2, and about 11% compared to that with TiO2using lactic acid as only chelator (Du et al.,2015).EquimolarAl2O3-TiO2 composite powders were  prepared via controlled  hydrolysis of organo-metallic precursors,sometimes in the presence of submicrometrecommercial ?-Al2O3 or anatase- The Microstructure andMorphology of 70% TiO2-30% Al, 70% TiO2-30% Al2O3,55% TiO2 – 45% Al and 55% TiO2-45% Al2O3composite powders were prepared by Smart Mini Ball Miller. They arecharacterized by XRD, SEM, EDAX, FTIR and TG/DSC.

The XRD results showed thatcomposite powders were mainly in the amorphous anatase phase with highcrystallinity. The SEM study of composite powders reveals the average particlesize is 100±20nm. In FTIR, peaks observed at around 460 cm-1to 560cm-1. The peaks at Ti-O-Ti bond and TiO2 lattice in FTIRspectra of TiO2-Al and TiO2-Al2O3 compositepowders confirm the formation of TiO2 based compound in thecomposite powders. The TG curve of 55% TiO2-0- -045% Al2O3showed weight loss where as that of 55% TiO2-45%Al showed weightgain and DSC curve showed formation and decomposition of composite powders (Mahalingam etal.

, 2017). The present investigation revealsthe effect of processing parameters on the properties of  Al2O3-TiO2nanocomposites.A polymer-assisted co-precipitation route has been employed tosynthesize Al2O3-TiO2 nanoparticles.

Thermalbehaviour of the prepared powder samples have been studied using differentialscanning calorimeter/thermal gravimetric analysis and dilatometer. Formation ofaluminium-titanate (Al2TiO5) phase has been confirmedusing X-ray diffraction analysis. Al2O3-TiO2nanocomposite powder can be sintered at 1650?C with more than 96% ofrelative density. Phase analysis of sintered sample shows formation of Al2TiO5phase (Singh et al.

,2017).Materials and methodsAl2O3and TiO2 will be prepared individually by the Sol-gel methodandthenmixingthe different ratio Of  TiO2 andAl2O3. Al2O3 nanoparticles will synthesize byusing ethanol solution of aluminum nitrate. At start Al(NO3)3.9H2Owas completely dissolved in pure water of ethanol solution will add drop bydrop to the solution at 800 °C. The white product will evaporated for 3 hoursand cool to room temperature then finally calcined at 500 °C for 5 Hours.

TiO2will be prepared by employing tetraisopropoxide (TiOCH(CH3)24;TIP) as a starting precursor. Ethanol and water will be employed as solvents,and HCl as an acidic catalyst. Using a sol-gel method, TTIP will be  ?rst dissolved in ethanol.

The mixture ofdistilled water and HCl will  be thenadded dropwise under vigorous stirring at room temperature. The mixture willfurther stirred for 3h, and the obtained gels will centrifuged, washed to removeexcess reactants and catalyst, and dried at 80°C for 24 h. Following the dryingprocess in the oven, the samples will becalcined at 500°C for 3 h at a heatingrate of 5°C/min. After preparing both TiO2 and Al2O3individually prepare Al2O3-TiO2 compositeby using different ratios.

Different ratios i.e 30% Al2O3and 70%  TiO2, 60% Al2O3and 40% TiO2, 90% Al2O3 and 10% TiO2 will prepared by mechano chemicalmethod (Rajender et al., 2016).Thestructural analysis of the samples was conducted by an X-ray Diffraction (XRD) system.

The morphology of the samples was studied by scanning electron microscopy(SEM).The UV  spectra of the samples weregenerated by a UV-Visible double-beam spectrophotometer and  used to calculate  their band gap (Alivisatos et al.,2004).