Aluminum Acetylacetonate Research Articles

Structure, isomerism, and vibrational assignment of aluminumtrifluoroacetylacetonate. An experimental and theoretical study

An interpretation of the experimental IR and Raman spectra of Aluminum (III) trifluoroacetylacetonate (Al(TFAA)3) complex, which were synthesized by us, is first reported here. The charge distribution, isomerism, strength of metal‑oxygen binding and vibrational spectral properties for this complex structure were theoretically investigated through population analysis, geometry optimization and harmonic frequency calculations, performed at B3LYP/6-311G* level of theory. In the population analysis, two different approaches reffered to as “Atoms in molecules (AIM)”, and “Natural Bond Orbital (NBO)” were used. According to the calculation resuls, the energy difference between the cis and trans isomers of Al(TFAA)3 is very small and indicates that both isomers coexist in the sample in comparable proportions. Comparison of the calculated frequency and intensity data with the observed IR and Raman spectra of the complex has supported this conclusion. On the other hand, comparison of the structural and vibrational spectral data of Al(TFAA)3, which were experimentally measured and calculated at B3LYP/6-311G* level, with the corresponding data of Aluminum acetylacetonate (Al(AA)3) has revealed the effects of CF3 substitution on the structural and vibrational spectral data associated with the CH3 groups in the complex structure.

A comparative study on physical properties of Al-doped zinc oxide thin films deposited from zinc acetate and zinc acetylacetonate by spray pyrolysis

Herein we present a comparative study on highly transparent, conductive aluminium-doped ZnO (AZO) thin films deposited by pneumatic spray pyrolysis (PSP) of a zinc acetate based solution and a zinc acetylacetonate based solution on soda lime glass. The structural, optical and electrical properties of the films were studied depending on aluminium content in the precursor solution and substrate temperature during deposition (Ts). The solution used to prepare AZO thin films contained 0.2 M zinc acetate or 0.2 M zinc acetylacetonate and aluminium acetylacetonate between 0–15 at.% [Al]/[Zn]. Substrate temperature was varied from 275 to 450 °C. Transmittance and reflectance spectra were recorded by UV-VIS-NIR spectroscopy. Resistivity, mobility and charge carrier density were determined by four point probe measurements in ambient conditions. According to X-ray diffraction analysis, AZO films are highly c-axis oriented until 2–3 at.% [Al]/[Zn] in the spray solution, depending on zinc precursor. Crystallite size is 25–30 nm for AZO films deposited at Ts 400 °C. All AZO films exhibited high average optical transmittance of 76–94% in the visible spectrum 400–800 nm wavelength range. Eg values ranged from 3.32 in undoped ZnO to 3.58 eV in in highly doped AZO films deposited from zinc acetylacetonate due to the formation of secondary AlOx phases. The lowest resistivities were obtained at Ts 400 °C for films deposited from zinc acetate, 3–7.5 at.% [Al]/[Zn] in solution (0.40 Ωcm) and at Ts 400 °C, 3–7.5 at.% [Al]/[Zn] in solution for films deposited from zinc acetylacetonate (0.47 Ωcm).

Optimization of fluoride removal from aqueous solution by Al2O3 nanoparticles

According to World Health Organization (WHO), fluoride has a narrow prescribed concentration level in drinking water (<1.5mg L−1) and defluoridation of water is necessary to remove elevated concentrations of fluoride from water. In the present work, aluminium acetylacetonate was used as a precursor which was dissolved in methanol to produce Al2O3 nanoparticles by flame spray pyrolysis (FSP) technique. Al2O3 nanoparticles were characterized by various techniques (e.g. Brunauer-Emmet-Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier Transform Infrared (FTIR) to get an insight of their physicochemical properties. The effects of different variable parameters such as solution pH (3−11), contact time (5–180min), initial fluoride concentration (0–30mg L−1), temperature (25, 35 and 45°C) and competing anions (chloride, nitrate, carbonate, sulfate and phosphate) were investigated to study the adsorption of fluoride from water. Among different kinetic and isotherm models studied, the pseudo-second-order model best described the kinetics, while equilibrium data were well fitted by the Langmuir isotherm model. The competing anions on defluoridation from water followed the order: phosphate>carbonate>sulfate>nitrate>chloride. Results from this study revealed the potential utility of Al2O3 nanoparticles for defluoridation of water.

Facile synthesis of AlO x dielectrics via mist-CVD based on aqueous solutions

Abstract Aluminum oxide (AlO x ) thin films were synthesized by mist-chemical vapor deposition (mist-CVD) using aluminum acetylacetonate (Al(acac) 3 ) dissolved in an aqueous solvent mixture of acetone and water. Nitrogen gas was used to purge the precursor solution and growth rates between 7.5–13.3 nm/min were achieved at substrate temperatures of 250–350 °C. The AlO x layers deposited at temperatures below 350 °C exhibit 3–5 at% residual carbon levels, however those grown at 350 °C exhibit only 1–2 at% carbon impurity. Reasonable dielectric properties were obtained in the latter, with a dielectric constant (κ) of ~ 7.0, breakdown field of ~ 9 MV/cm and relatively low leakage current density of ~ 8.3×10 −10 A/cm 2 .

Films Deposited from Reactive Sputtering of Aluminum Acetylacetonate Under Low Energy Ion Bombardment

Films were deposited from aluminum acetylacetonate (Al(acac)3) using a methodology involving reactive sputtering and low energy ion bombardment. The plasma was generated by the application of radiofrequency power to the powder containing electrode and simultaneously, negative pulses were supplied to the electrode where the substrates were attached. It was investigated the effect of the duty cycle of the pulses (Δ) on the properties of the coatings. Association of ion bombardment to the deposition process increased film thickness, structure reticulation and organic content. Ions from the deposition environment were implanted at the film-air interface or underneath it. Morphology and topography were altered depending on Δ. Considering the enhancement of Δ, it affected the flux of ions reaching the depositing interface and then the deposition rate, H content, crosslinking degree and surface microstructure. Alumina groups were detected in the infrared spectra, whereas the precipitation of amorphous alumina was confirmed by X-ray diffraction.

Ordered Mesoporous Alumina with Ultra-Large Pores as an Efficient Absorbent for Selective Bioenrichment

Alumina has recently turned out to be effective in enrichment of biomacrolecules like phosphopeptides due to its good affinity to phosphor groups. Ordered mesoporous alumina (OMA) materials with high surface areas, regular porous structures, and large pore size are an ideal absorbent for the enrichment of phosphopeptides. Herein, a ligand-assisted solvent evaporation induced coassembly route is developed to synthesize OMA materials with an ultralarge pore size (16.0–18.9 nm) using a high-molecular-weight poly(ethylene oxide)-b-polystyrene (PEO-b-PS) as a soft template, aluminum acetylacetonate as a precursor, and tetrahydrofuran as a solvent. The obtained ordered mesoporous alumina shows high surface area (114–197 m2/g), large pore volume (0.16–0.34 cm3/g), and high thermal stability (up to 900 °C). The OMA materials show crystalline γ-Al2O3 frameworks with crystal size of ∼11 nm after calcination at 900 °C in air. Because of their high surface area, ultralarge pore size, and rich Lewis acid sites, the ob...

Aerosol assisted chemical vapour deposition of transparent conductive aluminum-doped zinc oxide thin films from a zinc triflate precursor

The use of zinc triflate (trifluoromethanesulfonate), [Zn(OTf)2] as a precursor in the aerosol assisted chemical vapour deposition of zinc oxide thin films is described. Aluminum doped zinc oxide (AZO) thin films are also shown to be deposited when aluminum acetylacetonate [Al(acac)3] was introduced into the precursor solution, illustrating the versatility of this system. Film characterization techniques include glancing angle X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and optical and electrical measurements. AZO films with an Al content of 7at.% were found to have favourable transparent conducting oxide properties with simultaneous high transparency (>80%) in the visible light region and a low electrical resistivity (1.96×10−3Ωcm).

Facile synthesis of melt-spinnable polyaluminocarbosilane using low-softening-point polycarbosilane for Si–C–Al–O fibers

Melt-spinnable polyaluminocarbosilane (PACS) is of importance as the precursor to prepare the Si–C–Al–O ceramic fibers, which can be employed for the preparation of SiC fibers with high tensile strength and good thermal stability. In this work, low-softening-point polycarbosilane (LPCS) was synthesized by pyrolysis of polydimethylsilane and applied to prepare PACS precursors with variable aluminum content by the reaction with aluminum(III) acetylacetonate. GPC, 1H NMR, UV–Vis, FT-IR, 29Si NMR, 27Al MAS NMR, TGA, and elemental analysis were used to analyze the composition and structure of the PACS precursors. Finally, Si–C–Al–O fibers were obtained successfully by melt-spinning, curing, and final pyrolysis of the precursors. The method demonstrated in this work can be further extended to synthesize other melt-spinnable metal-containing polycarbosilane (PMCS, M: Zr, Ti, Fe, Co, et.) of high ceramic yield and adjustable M content by reacting LPCS with other corresponding metal-containing compounds.

Synthesis and characterization of Al2O3 nanoparticles by flame spray pyrolysis (FSP) — Role of Fe ions in the precursor

Iron doped aluminium oxide nanoparticles are of interest for number of applications (e.g. water treatment, catalytic conversion of exhaust gases) due to their high surface area, hardness, catalytic and magnetic properties. In the present study, flame spray pyrolysis (FSP) was employed for the synthesis of Fe/Al2O3 nanoparticles. Precursor solutions of aluminium acetylacetonate (0.2mol·L−1) and ferrocene (0 to 0.2mol·L−1) in toluene were used to synthesise pure and iron (Fe) doped Al2O3. The particle composition and morphology were studied and effect of iron concentration was analysed. It was found that in the absence of the iron precursor, FSP produced a mixture of two Al2O3 polymorphs: θ-Al2O3 and η-Al2O3. The addition of ferrocene as an iron precursor was found to suppress formation of θ-Al2O3. At an iron molar concentration of 0.2mol·L–1 mainly hercynite, FeAl2O4, was observed. Furthermore, increasing the iron concentration caused a linear shift of the X-ray diffraction peaks from positions corresponding to η-Al2O3 to those of FeAl2O4. This indicates the formation of a solid solution (FexAl2O3+x) at intermediated concentrations. It was also found that the primary particle size, which was below 10nm, did not significantly change with the increased iron concentration and was comparable to the mean crystallite size indicating that size of these single crystalline primaries is determined by the synthesis process rather than the chemistry of the product. However, the hydrodynamic size was around 180nm indicating that the particles are agglomerates in the water suspension. Additionally, zeta potential of the nanoparticles was found to decrease slightly with increasing iron content, though in all cases it was above 50mV. Finally, the potential of synthesized nanoparticles was examined for the removal of fluoride because fluoride causes harmful health effects to human health at elevated concentrations. The results of fluoride removal using synthesized nanoparticles produced in this study showed that the highest fluoride removal efficiency was observed for the sample having no iron content.

Effect of co-doping concentration on structural, morphological, optical and electrical properties of aluminium and indium co-doped ZnO thin films deposited by ultrasonic spray pyrolysis

In this work, we reported a chemical approach to prepare aluminium and indium co-doped ZnO thin films (AIZO) by ultrasonic spray pyrolysis. Film depositions were carried out on soda lime glass substrates at 425°C by using a spray solution containing zinc acetate as zinc precursor, aluminium acetylacetonate as Al dopant source and indium (III) acetate as In dopant source. Physical properties such as structural, morphological, optical and electrical properties were studied with respect to the equal variations in co-dopants concentration (0.5–3at%). X-ray diffraction patterns proved that films are poly crystalline with (002) preferential orientation. Scanning electron microscopy analysis showed that AIZO films grown like hexagonal nanopyramids, elongated grains and irregular trigonals. Optical transmittance ~85% and a minimum resistivity of 1.3×10−3Ωcm, are achieved for films when co-doped with 1.5at% of Al and 1.5at% of In, confirm that AIZO films are suitable for transparent conductive oxide (TCO) applications.

Determination and correlation of infinite dilution binary diffusion coefficients for aluminum acetylacetonate in supercritical and liquid fluids

The infinite dilution binary diffusion coefficients D12 for aluminum acetylacetonate in supercritical CO2 were determined at 308.15–333.15 K and at 7.80–40.00 MPa by the chromatographic impulse response (CIR) method. And, the diffusion measurements in liquid ethanol were carried out at 300.15–333.15 K and at 0.10 and 30.00 MPa by the Taylor dispersion method. It was found that the D12 values measured in supercritical CO2 show slowing down in the region of near critical point. The determined activation energies of diffusion were 23.0, 13.7, 12.0, 11.3 kJ/mol at 12.00, 20.00, 25.00, 35.00 MPa in supercritical CO2 and 19.1 kJ/mol at 0.10 MPa in liquid ethanol, respectively. All determined 90 diffusion data in this study can be correlated with the equation of D12 [m2/s] = 1.558 × 10−14 T [K] η [Pa s]−0.761 with average absolute relative deviation (AARD) of 5.6% over a wide fluid viscosity range from 2.462 × 10−5 to 1.258 × 10−3 Pa s.

Influence of Al, In codoping in enhancing the Figure of Merit of ZnO thin films for TCO Applications

ABSTRACTAIZO (Al and In codoped ZnO) thin films were deposited on soda lime glass substrates by the ultrasonic spray pyrolysis (USP) technique. The spraying solution was prepared from zinc acetate dihydrate, aluminum acetyl acetonate and indium acetate. Depositions were carried out at three different temperatures, 425, 450 and 475 °C. Structural, morphological, optical and electrical properties were examined with respected to the deposition temperatures. All AIZO films grown with (002) preferential orientation confirmed from X-ray diffraction analysis. Hexagonal nanostructures were observed from Scanning electron microscopy (SEM) analysis. Minimum electrical resistivity of 2.52 x10-3 Ω-cm was achieved for AIZO films.

Formation of TiO/Al2O3/C composite in thermal co-decomposition of aluminium(III) acetylacetonate and titanium(IV) oxyacetylacetonate

Thermal co-decomposition of Al(III) acetylacetonate-Ti(IV) oxyacetylacetonate mixture has been examined by using thermal gravimetry, differential scanning calorimetry and complementary analyses of evaporated products and solid residues by Fourier Transform Infrared, Raman and X-ray photoelectron spectroscopy, X-ray diffraction and scanning and transmission electron microscopy. The process is shown to differ from thermal decompositions of single acetylacetonates. Linear heating of the mixture allows predominant sublimation and minor degradation of Al(III) acetylacetonate along with extensive degradation of Ti(IV) oxyacetylacetonate to TiO2. Stepwise heating results in sublimation of one half of Al(III) acetylacetonate and co-decomposition of the residual chelates. The co-decomposition is judged to occur via an intermediary complex between both monomeric chelates. It primarily leads to an amorphous Ti, Al, C and O-containing phase which develops crystalline alumina and titanium monoxide upon annealing to high temperatures. The carbonaceous component of the amorphous phase assists in carbothermal formation and stabilization of titanium monoxide.

Vibrational spectroscopic study of sol–gel layered double hydroxides containing different tri- and tetravalent cations

Five different layered double hydroxides were synthesized from magnesium ethoxide in the presence of aluminium, gallium, indium, tin and zirconium acetylacetonates by using the sol–gel technique. The colloid suspensions initially obtained were gelled and separated by centrifugation. XRD patterns confirmed that the five solids thus obtained possessed a layered double hydroxide structure. Also, IR and Raman spectra revealed differences between the solids.

Film properties of alumina passivation layer for silicon solar cells prepared by spin-coating method

We prepared alumina passivation films deposited by a sol-gel wet process for silicon substrates. Aluminum acetylacetonate was used as a precursor, and the solution was spin-coated onto silicon substrates. Calcination temperature dependence of the passivation quality of the films was evaluated mainly by measuring effective lifetime using a photo conductance decay technique and capacitance–voltage measurements. Also, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were carried out to evaluate film properties. A large amount of negative fixed charge density (Qf=−3.1×1012cm−2) exists in the films calcined at 300°C. On the other hand, a long effective lifetime of 400μs was obtained for the sample calcined at 600°C, and the passivation films had a large amount of positive fixed charge density (Qf=3.6×1012cm−2) with a low interface state density.

Model Research On Deposition Of Pure Aluminium Oxide Layers By MOCVD Method

Abstract The purpose of this research is to develop an optimal method for synthesizing of nanocrystalline Al2O3 monolayers at high growth rates on cemented carbides coated with an intermediate layer of pre-Al2O3-C (composite layers Al2O3-C/Al2O3). The use of quartz glass substrate allows for obtaining information about the quality of the layers such the thickness and density, because of its high transparency. The Al2O3 layers that do not containing carbon were synthesized on quartz glass by MOCVD using aluminum acetylacetonate and air as the reactants at temperatures of 700-1000°C. Argon was also a carrier gas. The resulting layers were transparent, as homogeneous nucleation did not occur during the synthesis process. The layers synthesized at lower temperatures were subjected to a crystallization process at temperatures above 900°C. The crystallization process was studied as a function of time and temperature. The obtained layers were characterized by their nanocrystalline microstructure.

Model Research On Synthesis Of Al2O3-C Layers By MOCVD

Abstract These are model studies whose aim is to obtain information that would allow development of new technology for synthesizing monolayers of Al2O3-C with adjusted microstructure on cemented carbides. The Al2O3-C layer will constitute an intermediate layer on which the outer layer of Al2O3 without carbon is synthesized. The purpose of the intermediate layer is to block the cobalt diffusion to the synthesized outer layer of Al2O3 and to stop the diffusion of air oxygen to the substrate during the synthesis of the outer layer. This layer should be thin, continuous, dense and uniform in thickness. Al2O3-C layers were synthesized from aluminum acetylacetonate by the CVD method on quartz glass heated in an induction furnace in the temperature range 800-1000°C using argon as a carrier for the reactants. The layers were prepared also at low temperatures and were then subjected to crystallization at higher temperatures. The resulting layers prepared at temperatures above 900°C were nanocrystalline (including the α-Al2O3 phase). Due to the fact that crystallization can be controlled, we may have a greater influence on the structure and thus the properties of the layer compared to direct synthesis at high temperature.

Foamed mesoporous carbon/silicon composite nanofiber anode for lithium ion batteries

A new porous composite nanofiber manufacturing route, combining electrospinning and foaming processes, was developed. In this process, aluminum acetylacetonate (AACA) was introduced as the foaming agent in nanofibers made of polyacrylonitrile (PAN)/silicon (Si) nanoparticles. PAN/Si composite nanofibers were first produced through an electrospinning process and mesopores were then generated by foaming nanofibers via AACA sublimation. After further carbonization, the obtained mesoporous carbon/silicon composite nanofiber mats were tested as the anode material for lithium ion batteries. Within this composite anode, mesopores provide needed buffering space to accommodate the large volume expansion and consequent stress induced inside silicon during lithiation. This effectively mitigates silicon pulverization issue and helps achieve higher reversible capacity and better capacity retention in later battery tests when compared with anodes made of nonporous composites nanofibers and carbon nanofibers alone.

Innovative low temperature plasma approach for deposition of alumina films

Alumina films were deposited from a new plasma method using aluminum acetylacetonate (AAA) powder as precursor. The AAA was sputtered in argon and oxygen plasma mixtures. It was investigated the effect of the oxygen proportion (O2%) on the properties of the coatings. Deposition rate was derived from the layer height measured by profilometry. The elemental composition and molecular structure of the films were determined by Rutherford backscattering and infrared spectroscopies, respectively. Grazing incidence X-ray diffraction was used to investigate the microstructure of the films while hardness was determined by nanoindentation technique. Inspections on the surface morphology and on the film composition were conducted associating scanning electron microscopy and energy dispersive spectroscopy. Incorporation of oxygen affects the plasma kinetics and consequently the properties of the coatings. As moderated concentrations of oxygen (< 25%) are added, the structure is predominantly organic containing stoichiometric amorphous alumina. On the other hand, as high O2% (> 25%) are incorporated, the structure become rich in metallic aluminum with carbon rising at low proportions. The deposited layer is not homogeneous in thickness once the chemical composition of the precursor is changed by the action of the reactive oxygen plasma. Oxygen ablation on the film surface also contributes to the lack of homogeneity of the structure, especially as high oxygen proportions are imposed. Hardness data (0.5-2.0 GPa) corroborated the idea of an amorphous structure. Based on the results presented here it was possible to identify the oxygen concentration in the plasma atmosphere which mostly removed organics while preserving the stoichiometric alumina precipitation, subject of great relevance as one considers the reduction in the energy necessary for the creation of fully oxide coatings.

Rheological Behavior of Polycarbosilane Part II: Effect of Heterometal (Al) Content and Nature of Bonding with Si of Polycarbosilane

A few aluminum containing polycarbosilanes named AlOR-PCS and Alac-PCS have been synthesized by the reaction of aluminum isopropoxide (AlOR) and aluminum acetylacetonate (Alac) with polycarbosilane (PCS), respectively. These materials were characterized by Fourier Transform Spectroscopy (FTIR), Thermo gravimetric Analysis (TGA) and Gel Permeation Chromatography (GPC). The rheological properties of these compounds were studied with respect to time, temperature and atmosphere (inert & air). It has been observed that the increase in metal content enhances the crosslinking of the PCS chains. Under similar conditions, the crosslinking of AlOR-PCS derivatives was found slower than Alac-PCS. GPC analysis of the samples showed the increase in molecular weight of these compounds compared to virgin PCS. TGA showed improved ceramic yield with increasing metal content. Alac-PCS gave higher ceramic yield than AlOR-PCS for similar molar ratios of metal complexes.