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In this work, we have shown that aluminium acetylacetonate (Al(acac)3) can be used as the catalyst to synthesize Ti3+ self-doped TiO2 (Ti3+-TiO2) by sol–gel method in air. Ti3+-TiO2 can be obtained directly and Al(acac)3 is removed during the annealing process. Ti3+ concentrates in the surface layer of powders, making a homojunction between Ti3+-TiO2 in the surface layer and TiO2 in the bulk. Based on the scheme of Zielger-Natta catalysts and the characterization of the sols and gels of samples, the synthesis mechanism of Ti3+ is proposed as the combination of steric hindrance effect, Lewis acid-base reaction and crystal field effect and Al(acac)3 acts as the catalyst in the reaction. Charge generation, charge transport and interface reactions, all of the three crucial strategies of photocatalytic are improved through the self-doped Ti3+, resulting in enhanced photocatalytic and photoelectrochemical activities. Compared with the reported methods, this work proposes a simple and novel route for the preparation of Ti3+-TiO2, which would facilitate the preparation and application of TiO2 photocatalyst.

It can be found that reaction mechanisms and interactions between wood and organosilicone compounds have not been sufficiently explored. The aim of the study was to determine bonds formed between either cellulose or lignin and methyltrimethoxysilane (MTMOS) during a catalytic silanization reaction. Silanization was performed in the presence of two catalysts of a diverse mechanism of functionalization: aluminum acetylacetonate (Al(acac)3) and acetic acid (AcOH). For this purpose, FT-IR, 13C and 29Si NMR techniques were used. Cellulose silanization efficiency without a catalyst was unlikely. Lignin undergoes a silanization reaction with alkoxysilanes much easier than cellulose. The results showed new bonds between biopolymers and the silanising agent. The new bonds were confirmed by signals at the FT-IR spectra, e.g., 770 cm&minus, 1 and 1270 cm&minus, 1 (Si&ndash, CH3), and at the NMR signal coming from the T1, T2 and T3 structures. Efficiency of reaction was confirmed by atomic absorption spectroscopy (AAS) analysis.

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 (0.5–3 at%). 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 1.3×10−3 Ω cm, are achieved for films when co-doped with 1.5 at% of Al and 1.5 at% of In, confirm that AIZO films are suitable for transparent conductive oxide (TCO) applications.

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 (0.2 mol·L− 1) and ferrocene (0 to 0.2 mol·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 0.2 mol·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 10 nm, 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 180 nm 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 50 mV. 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.

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).

In this work, Al doped ZnO (AZO) thin films were deposited on soda lime glass substrates at 275 °C by MOCVD using ultrasonic atomization and the effects of Al doping concentration on the structural, electrical and optical properties of AZO films were investigated. Zinc acetylacetonate and aluminium acetylacetonate were used for the source precursors of Zn and Al, respectively. Al doping enhanced the [001] preferred orientation and crystallinity of films. The resistivity of AZO thin film was decreased with the increase of doping ratio up to 6 mol%. The lowest resistivity obtained in this experiment was about 6.0 × 10−4 Ω · cm. The average optical transmittance in the visible wave length range was over 90 % for all of the films regardless of doping concentration. The optical band gap of AZO thin films was increased with the increase of Al doping concentration.

Even though aluminium is not considered to be a heavy metal like lead, silver, arsenic and cadmium, it can be toxic when taken in excessive amounts and even in small amounts if deposited in the brain. Glutathione, a major antioxidant in the cells, so its depletion weakens the tissue resistance to oxidant. Glutathione is the sulfhydryl (-SH) antioxidant, antitoxin and enzyme cofactor which plays an important role in aluminum detoxification. The present study was designed to investigate the extent of changes in glutathione level by inorganic and organic alumni metal. Biocordination of aluminum acetylacetonate and aluminum sulphate with glutathione in T-cells and b-cells of lymphocytes have been described using Ellman’s method. The decline of glutathione level is due to increased aluminum concentration and time of incubation. The decline of glutathione level was consistent with increasing pH, while at physiological temperature, the drop was more significant. Our study indicates that changes in glutathione level produced by aluminium could be due to conjugate (Al-(SG)3) formation. This change in glutathione level endowed with information regarding mechanism of toxicity of aluminium inorganic and organic complexes. This study is important for the design of rational antidote for the prevention of aluminium toxicity. Key words: Glutathione (GSH), aluminium sulphate Al2(SO4)3, aluminium acetylacetonate (Al(acac)3) , T-cells, B-cells.

According to World Health Organization (WHO), fluoride has a narrow prescribed concentration level in drinking water (< 1.5 mg 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 (5–180 min), initial fluoride concentration (0–30 mg 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., final draft, peerReviewed

Silica aerogel granules have been synthesized by doping aluminium acetylacetonate (Al(acac)3) and Copper acetylacetonate (Cu(acac)2), in the sol of tetraethoxysilane followed by ambient pressure drying process. The well established silica network provides effective confinement for metal particles which resists the collapse of silica network during ambient pressure drying of wet gel. In this paper, the effect of Al(acac)3 and Cu(acac)2 on physico-chemical properties of the aerogels have been studied by varying the concentration of both from 0.0005 to 0.05 M. The chemical composition, hydrophobicity and elemental analysis of Al(acac)3 and Cu(acac)2 doped silica aerogels were studied by using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, contact angle measurement, X-ray diffraction, atomic absorption spectroscopy. The morphological study was carried by using transmission electron microscopy and surface area and pore diameter was measured by BET analysis. The thermal stability of hydrophobic nature was analyzed by simultaneous thermogravimetry and differential scanning calorimetry. The Al(acac)3 added silica aerogels are found to be superhydrophobic, low dense, high surface area and optically transparent as compared with Cu(acac)2 doped silica aerogels.

The crosslinking behaviour of a silicone resin which is interesting from a technical point of view was investigated by means of rheology. In order to accelerate the crosslinking process, zinc acetylacetonate and aluminium acetylacetonate were applied as latent catalysts. The effect of the type of catalyst, its concentration, and the temperature on crosslinking was determined by isothermal dynamic-mechanical measurements. A radial gradient in crosslinking causes the gel point to be reached earlier at the outer edge of the sample in the rheometer. This radial gradient is averaged when measuring G′ and G″. Therefore, since the physically well-defined state of critical gelation (gel point) could not be obtained from the data, the time at which a distinct crosslinking state is reached was determined by the crossover of the moduli G′ and G″. For this distinguished point, the denotation gelation index GI is introduced. The gelation indices measured at different temperatures follow an Arrhenius-type relationship. Activation energies between 89 and 126 kJ/mol were determined. They were found to be dependent on the type of catalyst used but independent of its concentration. The activation energies of the crosslinking processes enable the calculation of the gelation index at temperatures not measured directly.

Highly transparent, conductive ZnO films have been deposited by spray pyrolysis of a zinc acetate based solution. Quality films are yielded as our process is analogous to an aerosol assisted chemical vapour deposition rather than a droplet deposition spray pyrolysis technique. The properties of the films are governed by the additives to the base precursor solution. When aluminium acetylacetonate is added to the precursor solution, ZnO:Al films are grown with free charge carrier concentrations of more than 1020 cm−3. The carrier density and mobility are measured by both Hall probe and near infrared spectroscopy. Film growth and grain size, morphology and orientation are altered using an increased percentage of ZnCl2 in the precursor, which results in a 10 fold increase in charge carrier mobility. An investigation is presented correlating the composition of the precursor solution with the chemical, structural, electrical and optical properties of the grown films.

Nanocrystalline FeAl 2 O 4 has been synthesized from furnace heating of corresponding iron and aluminium acetylacetonate complexes. The nanoparticles obtained were characterized using powder X-ray diffraction (XRD), EDX and transmission electron microscopy (TEM). The particles were faceted with a diameter in the range of 10–20 nm. The magnetic property of the FeAl 2 O 4 nanoparticles was studied for the first time by plotting M vs H hysteresis curves, at different temperature and also by recording the temperature dependence of zero-field-cooled M ZFC and field-cooled M FC magnetization curves. On decreasing the temperature to 4 K, the magnetization shows deviation from linear behavior.

A combustion CVD process with aluminium acetylacetonate as a precursor was used to apply alumina on a float glass surface at a temperature of 600 °C in order to improve its hydrolytic resistance. The generated surfaces were investigated by XPS, SEM, AFM, and leaching experiments. It was found that fine alumina particles were generated, which cover the surface, and that the percentage of alumina on the surface determined its hydrolytic resistance. While there was no diffusion of aluminium into the glass matrix detected, deposited alumina demonstrated a measurable influence on the sodium–silicium-ratio at the glass surface.

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Alumina is one of the most common and stable metal oxides in nature, which has been developed as a novel adsorbent in enrichment of biomolecules due to its excellent affinity to phosphor or amino groups. In this study, ordered mesoporous alumina (OMA) with interconnected mesopores and surface acidic property is synthesized through a solvent evaporation induced co-assembly process using poly(ethylene oxide)-b-polystyrene (PEO-b-PS) diblock copolymer as a template and aluminium acetylacetonate (Al(acac)3) as the aluminium source. The pore size (12.1–19.7 nm), pore window size (3.5–9.0 nm) and surface acidity (0.092–0.165 mmol g−1) can be precisely adjusted. The highly porous structure endows the OMA materials with high hemoglobin (Hb) immobilization capacity (170 mg g−1). The obtained Hb@OMA composite is used as an electrocatalyst of biosensor for convienet and fast detection of hydrogen peroxide (H2O2) with a low H2O2 detection limit of 1.7 × 10−8 m and a wide linear range of 2.5 × 10−8 to 5.0 × 10−5 m. Moreover, the Hb@OMA sensors show a good performance in real time detection of H2O2 released from Homo sapiens bone osteosarcoma, indicating their potential application in complex biological processes. This work was supported by the NSF of China (51372041, 51422202, 21673048, 91749204 and 81771491), Shanghai Pujiang Program, China (No. 16PJ1401100), Key Basic Research Program of Science and Technology Commission of Shanghai Municipality (17JC1400100), Shanghai Municipal Science and Technology Commission Key Program (15411950600), Youth Top-notch Talent Support Program of China, the state key laboratory of Transducer Technology of China (Grant No. SKT1503), the Outstanding Talents Cultivation Program of Shanghai Health System (2017BR011), and Qatar University under GCC Co-Fund Program, Grant GCC-2017-001. The authors thank Prof. Guangrong Zhou for assistance in TEM characterization.

Polyaluminocarbosilane was synthesized by direct reaction of polydimethylsilane with aluminum(Ⅲ)-acetylacetonate in the presence of zeolite catalyst. A fraction of higher molecular weight polycarbosilane was formed due to the binding of aluminium acetylacetonate radicals with the polycarbosilane backbone. Small amount of Si-O-Si bond was observed in the as-prepared polyaluminocarbosilane as the result. Polyaluminocarbosilane fiber was obtained through a melt spinning and was pyrolyzed and sintered into SiC fiber from 1200~2000℃ under a controlled atmosphere. The nucleation and growth of β-SiC grains between 1400 - 1600℃ are accompanied with nano pores formation and residual carbon generation. Above 1800℃, SiC fiber could be sintered to give a fully crystallized β-SiC with some α-SiC.

The organometallic vapour deposition of aluminium oxide films in a cold wall reactor was studied at temperatures between 773 and 1273 K and the pressure range of 55–1000 hPa. Aluminium acetylacetonate and oxygen were used as precursors. All films were characterized by scanning electron microscopy, electron dispersive X-ray spectroscopy and X-ray diffraction. Film growth at low pressure (55 hPa) was analyzed as a function of the deposition temperature: It is mainly surface kinetically controlled, and films grown at low temperatures ( 2 O 3 , θ-Al 2 O 3 , and α-Al 2 O 3 . These crystalline films are spalling. In addition, the influence of the total pressure on the deposition was studied for high deposition temperatures (1273 K): Film growth was significantly faster at pressures below 300 hPa. Additionally, a phase change is observed with increasing pressure: Films deposited at 55 hPa consist of three phases, γ-Al 2 O 3 , θ-Al 2 O 3 , and α-Al 2 O 3, whereas above 200 hPa mainly the latter two phases are observed. Films grown at high pressures above 200 hPa are better adhering.

Aluminium oxide nanoparticles were synthesized by a chemical vapor condensation process using aluminium acetylacetonate as a precursor in the temperature range of 700 – 1000 °C. From X-ray diffraction results, it was found that the δ-Al2O3 phase was obtained at 900 °C and 1000 °C. Transmission electron microscopy observation revealed that δ-Al2O3 nanoparticles 10 – 15 nm in diameter consisted of a hollow structure with shells 2 – 3 nm in thickness. The sequential decomposition of acetylacetonate groups observed in thermogravimetry analysis showed that the formation of a hollow structure depends on the characteristics of the metal – organic precursor. Also, a decrease in the transmittance of δ-Al2O3 nanoparticles was found in the wavelength range of 300 – 900 nm by UV-Visible spectrophotometry, which is expected to occur by scattering and absorption of light depending on particle size and hollow structure.

Solvent-based UV-crosslinkable pressure-sensitive adhesives (PSA) present a new class of products that offers the potential to produce a novel generation of ultraviolet cured self-adhesive products with excellent shrinkage resistance. A variety of solvent-based pressure-sensitive adhesives were prepared by synthesis in ethyl acetate with solid content on 50 wt.% with 2-ethylhexyl acrylate, methyl acrylate, acrylic acid, N-vinyl caprolactam and unsaturated photoinitiators: 4-acryloyloxy benzophenone, allyl benzoine and phenyl-(1-acryloyloxy)-cyclohexyl ketone. The main emphasis is given to the influence of viscosity and molecular mass of synthesized adhesive on their shrinkage. Further trials show the effect of the UV-crosslinking process with UV-lamp and comparison with acrylics PSA crosslinked with metal chelates aluminium acetylacetonate and titanium acetylacetonate on shrinkage. Further examinations describe the influence of various factors such as UV exposure time and UV dose on very relevant PSA performance such as shrinkage on coated PVC carrier.

A polysilane (PS) has been modified chemically with aluminium acetylacetonate (AlAce) to prepare new Si‐Al‐C‐O precursors. Chemical reactions occur between PS and AlAce and this gives rise to higher pyrolysis yields from the precursors at 900°C in nitrogen, compared with that of PS, due to network formation by crosslinking. Further pyrolysis of the precursors to 1700°C in nitrogen produces ceramics of the SiC‐AlN system with composition dependent on the AlAce/PS ratio. The structures of the precursors and their pyrolysis products have been characterized and the influence of the AlAce/PS ratio has been elucidated.

Aluminium-doped zinc oxide thin films were deposited from zinc acetylacetonate and aluminium acetylacetonate at various aluminium concentrations and deposition temperatures by ultrasonic spray pyrolysis. The structural and morphological properties and elemental composition of these films were studied by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy, respectively. The gas sensing properties were studied by a two-point probe in O_2/99% N_2 and H_2/97% Ar at operating temperatures of 60, 80, and 100 °C. The films were composed of hexagonal wurtzite-type zinc oxide. The surface morphology of the films depends on the amount of aluminium doping. The hydrogen sensing capability of aluminiumdoped zinc oxide thin films deposited from 5 at% Al/Zn solution decreased from 11% to 5.5% as deposition temperature was increased from 280 to 400 °C, but the stability improved by an order of magnitude. The highest sensor response (8%) to 3 vol% H_2 in Ar was observed at an operating temperature of 100 °C in the film deposited at a substrate temperature of 400 °C from the solution containing 2 at% Al/Zn. Aluminium doping above 2 at% Al/Zn in the solution reduced film resistance by up to two orders of magnitude and sensor response decreased to 3% at 100 °C. Response times as low as 3 s were observed when detecting hydrogen at operating temperatures 60-100°C.

Metalorganic Chemical Vapour Deposition is a promising method for the growth of thin aluminium doped zinc oxide films (ZnO:Al), a material with potential application as transparent conducting oxide (TCO), e.g. for the use as front electrode in solar cells. For the low-cost deposition, the choice of the precursors is extremely important. Here we present the deposition of quite homogeneous films from the acetylacetonates of zinc and aluminium that are rather cheap, commercially available and easy to handle. A user-made CVD-reactor activating the deposition process by the light of halogen lamps was used for film deposition. Well-ordered films with an aluminium content between 0 and 8% were grown on borosilicate glass and Si(100). On both types of substrate, the films are crystalline and show a preferred orientation along the (002)-direction. The 0.3 to 0.5 μm thick films are highly transparent in the visible region. The best films show a low electric resistivity between 2.4 and 8 mΩ cm.

A study of the deposition of aluminium oxide films by low-pressure metalorganic chemical vapour deposition from the complex aluminium acetylacetonate, in the absence of an oxidant gas, has been carried out. Depositions on to Si(100), stainless steel, and TiN-coated cemented carbide are found to be smooth, shiny, and blackish. SIMS, XPS and TEM analyses reveal that films deposited at temperatures as low as 600 degreesC contain small crystallites Of kappa-Al2O3, embedded in an amorphous matrix rich in graphitic carbon. Optical and scanning electron microscopy reveal a surface morphology made up of spherulites that suggests that film growth might involve a melting process. A nucleation and growth mechanism, involving the congruent melting clusters of precursor molecules on the hot substrate surface, is therefore invoked to explain these observations. An effort has been made experimentally to verify this proposed mechanism. (C) 2002 Elsevier Science B.V. All rights reserved.

Spectroscopic ellipsometry was used to characterize carbonaceous, crystalline aluminium oxide films grown on Si(100) by low-pressure metal organic chemical vapour deposition, using aluminium acetylacetonate as the precursor. The presence of carbon in the films, attributed to the use of a metalorganic precursor for the deposition of films, was identified and analysed by secondary ion mass spectroscopy and X-ray photoelectron spectroscopy, for the elemental distribution and the chemical nature of the carbon in the films, respectively. Ellipsometry measurements over the photon energy range 1.5-5 eV were used to derive the pseudo-dielectric function of the aluminium oxide-containing films. Multi-layer modelling using linear regression techniques and the effective medium approximation were carried out to extract the structural details of the specimens. The excellent fit between the simulated and experimental optical data validates the empirical model for alumina-containing coatings grown by MOCVD.

A novel laser assisted open atmosphere CVD/pyrolysis technique, for the synthesis of dense, hard nanostructured oxide coatings, has been successfully developed in-house. In this process 0·5 to 2·5 μm size droplets of an appropriate metal organic compound/metal nitrate dissolved in a suitable solvent were transported into a quartz tube, using a carrier gas. To this tube a CW Nd: YAG laser (1064 nm) was coaxially coupled. The laser, upon interaction with the precursor, caused its vaporisation/activation. The activated precursor aerosols and the laser were made to impinge the substrate which is placed at an optimum distance. The activated aerosol reacts with oxygen present in the atmosphere at the laser heated spot on the substrate surface to give an oxide coating. Nanostructured alumina coatings were synthesised on steel substrates using aluminium acetylacetonate in ethanol as well as aluminium nitrate solution as the precursors. YSZ coatings were produced using zirconyl and yttrium nitrate mixture (Zr∶Y = ...

The crystalline and structural characteristics of aluminium oxide (Al2O3) thin films deposited by ultrasonic spray pyrolysis have been analysed using conventional and high resolution transmission electron microscopy. The aluminium oxide films were deposited on silicon (100) wafers, using a solution of aluminium acetylacetonate in dimethylformamide. The films were deposited with and without the addition of water mist generated in parallel to the spraying solution. The substrate temperatures during deposition of the films were in the range of 500-650 °C. The results indicate that the thin films deposited without water mist have an amorphous structure, while those films deposited with the addition of water mist show a two-face nature, formed by small crystallites embedded in an amorphous matrix. The crystalline phase has been determined, through the indexing of the electron diffraction patterns. It is found that it corresponds to 5Al2O3 · H2O in a Tohdite hexagonal structure with unit cell lattice constants a = 5.575 A and c = 8.76 A.

Elastic and thermoelastic properties of the 21 title crystalline species have been determined from ultrasonic resonant frequencies of plates and their shift upon variation of temperature, respectively. In addition, the tensors of thermal expansion have been measured by the aid of a Fizeau interferometer. An analysis of the elastic behaviour of organic crystals, including earlier elastic data of other organic compounds taken from the literature, revealed common features of organic crystals and organic liquids in respect to the scalar invariantsC= (c11+c22+c33+c44+c55+c66+c12+c13+c23)/9 and d logC/dT,Ttemperature, especially in the case of Van-der-Waals crystals. Contrary to ionic crystals the invariantCincreases in these crystals with larger molecular volume. Crystals with strong hydrogen bonds like dicarboxylic or sulfonic acids behave rather like ionic crystals. The influence of a small molecular elastic stiffness, as observed in plastic crystals, is clearly recognizable in the elastic properties. The impact of structural details on the invariantCand its logarithmic temperature derivative is surprisingly small.

Highly conductive and transparent ZnO thin films were prepared by atmospheric pressure CVD on glass substrates in the temperature range from 375 to 475°C. Aluminium acetylacetonate or gallium acetylacetonate were used as the dopant source of group III element. The resistivity of the films critically depends on the amount of dopants and changes in a range of 10−1 to 10−3 Ω cm. The lowest resistivity of 2.0×10−3 Ω cm was obtained in the Ga-doped films deposited at the substrate temperature of 425°C. X-ray diffraction results show that all deposited films were polycrystalline in nature with (002) preferred orientation. The electron concentration and Hall mobility of the film with the lowest resistivity are 5.9×1019 cm−3 and 31 cm2 V−1 s, respectively.

Coating films of CH 3 SiO 3/2 on sapphire, SiO 2 glass, and metallic substrates have been prepared from an aluminium acetylacetonate catalyzed oligomer solution. The coating films are treated in atmospheres of gaseous amines. The reaction is monitored by using an infrared absorption of Si OH at 3000–3700 cm −1 . The polymerization of silanols in the coating films proceeds at an elevated treatment temperature. The degree of polymerization becomes larger with the exposure to amines, indicative of a catalytic effect of gaseous amines on the polymerization.

Using 27 Al ( I =5/2) NMR of aluminium acetylacetonate, we show that it is possible to cross-polarize from a spin I =1/2 nucleus ( 1 H ) directly to the central triple-quantum transition of a half-integer quadrupolar nucleus ( 27 Al ) in a powdered sample under MAS conditions. The optimum conditions for this multiple-quantum cross-polarization (MQCP) are investigated experimentally and compared with existing theoretical results. The new technique is applied to the recently introduced two-dimensional MQMAS experiment for recording high-resolution NMR spectra of half-integer quadrupolar nuclei.

The hydrodynamic behaviour of a very dense tungsten powder, 75 μm in median diameter and 19,300 kg/m 3 in grain density, has been studied in a fluidized bed at room temperature using nitrogen and argon as carrier gas. Even if fluidization was achieved, the small bed expansion indicated that it was imperfect. Then, the fluidization was studied at 400 °C in order to investigate the feasibility of coating this powder by Fluidized Bed Chemical Vapour Deposition (FBCVD). In particular, the influence of the H 0 / D ratio (initial fixed bed height to reactor diameter) on the bed thermal behaviour was analyzed. It appeared that at least 1.5 kg of powder (corresponding to a H 0 / D ratio of 1.8) was necessary to obtain an isothermal bed at 400 °C. Finally, first results about alumina coatings on the tungsten powder by FBCVD from aluminium acetylacetonate are detailed. They show that for the quite low temperatures tested, the coatings are uniform on all bed particles and are formed of amorphous carbon containing alumina. This study demonstrates the efficiency to combine fluidization (instead of spouted bed) and CVD to coat such very dense powders.

Al-doped ZnO nanoparticles are synthesized by means of a heating up solution based thermal decomposition method. The synthesis involves a reaction of zinc acetylacetonate hydrate, aluminium acetylacetonate and 1,2-hexadecanediol in the presence of oleic acid and oleyl amine. A proposed reaction mechanism from reagents to monomers is corroborated by analysis of the evolving gases using headspace GC-MS analysis. The Al-doped ZnO nanoparticles synthesized are dynamically stabilized by adsorbed oleate ions, after deprotonation of oleic acid by oleyl amine, as was found by NOESY proton NMR and complementary FTIR spectroscopy. Precession electron diffraction shows a simultaneous increase in lattice parameters with Al concentration. This, together with HAADF-STEM and EDX maps, indicates the incorporation of Al into the ZnO nanoparticles. By the combination of complementary characterization methods during all stages of the synthesis, it is concluded that Al is incorporated into the ZnO wurtzite lattice as a dopant.

A SiO 2 powder has been coated by alumina using the Fluidized Bed Chemical Vapor Deposition process and a metal organic precursor, aluminium acetylacetonate (Al(acac) 3 or C 15 H 21 AlO 6 ) as single source. A range of low temperatures, i.e. 400–620 °C has been explored at atmospheric pressure. Systematic characterizations were performed by Field Emission Gun Scanning Electron Microscopy (FEG-SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infra-Red (FT-IR) spectroscopy and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). The process involves a first step of gas phase reactions producing reactive intermediates, themselves leading to Al 2 O 3 and carbon containing deposits. Between 400 and 500 °C, the deposits are lamellar and constituted of mixtures of Al 2 O 3 , non-decomposed Al(acac) 3 and impurities, leading to a C/Al molar ratio close to 2. For this range of temperature, the precursor is not totally decomposed and the limiting parameter of the process is the deposition temperature. For 600 and 620 °C, the deposits are nodular and mainly formed of Al 2 O 3 and acetylacetone C 5 H 8 O 2 , one of the main intermediate species formed in the gas phase. The Al(acac) 3 decomposition seems to be complete, but a deposition temperature of 620 °C is not high enough to allow a complete decomposition of carbon ligands of the chemisorbing intermediate species. For these conditions, the C/Al molar ratio increases with the deposition temperature, to reach values between 4 and 6, in agreement with the observed darker colors of the deposits.

The diffusion coefficient data for organometallic substances are scarce in the literature. A recently developed quartz crystal microbalance (QCM) system has been used to measure the binary diffusion coefficients. The system consists of a QCM with a driving oscillator circuit, a closed Stefan tube, a temperature controlled unit, a data logger, and a frequency counter. The QCM crystal is placed on the top of a Stefan tube and its active surface is coated with a thin layer of the substance. On the other end of the Stefan tube highly adsorptive charcoal powder is placed. Thus a mass concentration gradient is established in the diffusion tube. The rate of mass loss from the QCM was then used to determine the binary diffusion coefficient in air. Diffusion coefficients of polyaromatic hydrocarbons anthracene and phenanthrene and some organometallic compounds (e.g. ferrocene, aluminium acetylacetonate and chromium acetylacetonate) in air at various temperatures are reported.

The synthesis of aluminium nanoparticles in a polypropylene (PP) matrix by a sol–gel process in the melt was investigated. The study was performed using two aluminium precursors, aluminium isopropoxide and aluminium acetylacetonate, to assess the effect of the stereochemical hindrance of the precursor organic groups on reactivity. The hybrid nanocomposites were prepared in a batch mixer under constant processing conditions and characterized by several techniques. Chemical and morphological character- ization proved that aluminium formed covalent bonds with polypropylene modified with maleic anhy- dride and the presence of aluminium nanoparticles. Moreover, TEM micrographs of both nanocomposites synthesised revealed a lower amount of nanoparticles when aluminium acetylacetonate was used. The values of the activation energy determined explained the higher reactivity of aluminium isopropoxide. The reaction mechanisms were proposed for both precursors., The authors acknowledge the Foundation for Science and Technology (FCT) Project SFRH/BD/39085/2007 for the financial support.

Highly transparent conducting undoped and Al-doped ZnO (ZnO:Al) films were prepared by atmospheric pressure chemical vapour deposition using zinc acetylacetonate (Zn(C 5 H 7 O 2 ) 2 ) zinc source and aluminium acetylacetonate (Al(C 5 H 7 O 2 ) 3 ) dopant materials. The film growth and electrical properties were considerably affected by the choice of oxygen source such as air and H 2 O. Milky undoped ZnO and ZnO:Al films with texture surface were prepared with thickness above 400 nm. The minimum resistivities of 7.1 × 10 −3 and 3.4 × 10 −3 ω cm were obtained in milky ZnO:Al films prepared at substrate temperature of 350 °C with H 2 O and 550 °C with air respectively. For use at high temperatures, the resistivity of ZnO:Al films was more stable than that of undoped ZnO films. A sheet resistance as low as 32 ω/◊, a transmittance of 81% and a haze ratio of 62% at a wavelength of 550 nm were obtained for milky ZnO:Al films 1000 nm thick prepared at 350 °C with H 2 O.

Cobalt catalysts obtained from the reduction of Co(acac) 2 with Al(Et) 3 have been studied by infrared spectroscopy (in the selective hydrogenation of multifunctional compounds). These solids prepared in situ were in suspension in a liquid mixture containing solvent and reagent. In order to obtain information on the preparation and the composition of the catalyst we carried out an FT-IR characterization using a special device warranting sample manipulation in air-free atmosphere. At room temperature there were instantaneous and reductive ligand-exchange between Al(Et) 3 and Co(acac) 2 and formation of Co 0 particles, Co 0 soluble complexes and Al(Et) 2 (acac). The multistep process may be initiated through the formation of a donor-acceptor complex ((acac)Co(acac)→Al(Et) 3 ). The presence of CO in the gas phase (H 2 ) when heating the reaction mixture up to 180°C enhances the reduction of cobalt and probes Co 0 in different coordination symmetries. Some of the Co 0 species could be surrounded with cobalt alkoxide species and aluminium acetylacetonate.

Transparent and conducting zinc oxide (ZnO) films have been prepared on glass substrates by atmospheric and low pressure chemical vapour deposition (CVD) using zinc acetylacetonate (Zn(C 5 H 7 O 2 ) 2 ) and various oxygen sources such as air, water (H 2 O) and hydrogen peroxide (H 2 O 2 ). A resistivity of (4–6) × 10 −3 Ω cm and an average transmittance above 80% in the visible range were obtained for undoped ZnO thin films prepared at a substrate temperature of 550°C using H 2 O or H 2 O 2 . It was found that H 2 O and H 2 O 2 , which include hydrogen, were better oxygen sources than an oxygen-containing gas such as air. The deposition rate of ZnO films was controlled by the Zn(C 5 H 7 O 2 ) 2 temperature. Al-doped ZnO films with a resistivity as low as 4.6 × 10 −3 Ω cm were prepared at a substrate temperature of 350°C by CVD at a low pressure of 60 Torr using aluminium acetylacetonate (Al(C 5 H 7 O 2 ) 3 ) as the dopant source.

In order to study the feasibility of coating very dense powders by alumina using Fluidized Bed Metal Organic Chemical Vapour Deposition (FB-MOCVD), experiments were performed on a commercial tungsten powder, 75 nanometers in median volume diameter and 19,300 kg/m3 in grain density. The first part of the work was dedicated to the experimental study of the tungsten powder fluidization using argon as carrier gas at room temperature and at 400 °C. Due to the very high density of the tungsten powder, leading to low initial fixed bed heights and low bed expansions, different weights of powder were tested in order to reach satisfactory temperature profiles along the fluidized bed. Then, using argon as a fluidized bed former and aluminium acetylacetonate Al(C5O2H7)3 as a single source precursor, alumina thin films were deposited on tungsten particles at a low temperature range (e.g., 370–420 °C) by FB-MOCVD. The influence of the weight of powder, bed temperature and run duration was studied. Characterizations of the obtained samples were performed by various techniques including scanning electron microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS) analyses, Field Emission Gun SEM (FEG-SEM) and Fourier Transform InfraRed (FT-IR) spectroscopy. The different analyses indicated that tungsten particles were uniformly coated by a continuous alumina thin film. The thickness of the film ranged between 25 and 80 nm, depending on the coating conditions. The alumina thin films were amorphous and contained carbon contamination. This latter may correspond to the adsorption of species resulting from incomplete decomposition of the precursor at so low deposition temperature

27Al CP / MAS NMR spectra of aluminium acetylacetonate show distinct lineshapes depending on the experimental conditions as the different orientations within the powder cross-polarize with differing efficiencies. Selective polarization transfer to the 1 2 ↔ −1 2 transition occurs at rf power levels corresponding to 3ωAl=ωH, while non-selective polarization transfer can occur at higher27 Al rf powers. Two-dimensional quadrupole nutation spectra show that the cross-polarization lineshapes arise principally because the different orientations have different 27 Al nutation frequencies. The results obtained highlight the caution needed in the interpretation of CP/MAS NMR spectra of quadrupolar nuclei.

Réalisation de couches minces de phosphate d'aluminium sur substrat de silicium à partir des précurseurs tributylphosphate et acétylacétonate d'aluminium en solution par la méthode “pyrosol". La composition chimique des dépôts varie rapidement en fonction des conditions expérimentales. Ces couches minces sont caractérisées par spectrométrie infrarouge et diffraction des RX. Leurs caractéristiques électriques, déterminées par conductivité électrique en courant continu et alternatif, sont nettement différentes de celles du phosphate d'aluminium cristallisé et s'expliquent par l'existence de “liaisons pendantes” AI-O et P-O.

Thin films of aluminium oxide have been deposited on glass, quartz, Si(100), steel, nickel, and aluminium by plasma-enhanced chemical vapour deposition (PECVD) using aluminium acetylacetonate (Al(acac)3) as precursor. The deposits are hard (up to 2370 HK) and show good adherence to the substrates. The influence of various experimental parameters on deposition rate, film composition and hardness has been studied. The bias turned out to be the most effective parameter.