7429-90-5

In this study, Al was electrodeposited on a platinum substrate at room temperature from an ionic liquid bath of EMIC containing AlCl3 using potentiostatic polarization (PP), galvanostatic polarization (GP), monopolar current pulse polarization

Better than water: A method for the electrodeposition of nanocrystalline metals and alloys from ionic liquids has been developed (see schematic representation). This method enables the synthesis of aluminum nanocrystals with average grain sizes of about 10 nm, Al-Mn alloys, as well as Fe and Pd nanocrystals.

A finite-element model of the electrodeposition of aluminium from chloroaluminate ionic liquids is introduced. The purpose of this model is to give an explanation for the reasonable current densities that can be achieved in chloroaluminate ionic liquids despite the fact that the electrochemically active Al 2 Cl 7 - complexes are transformed into inactive AlCl 4 - complexes during the electrodeposition of aluminium. The obtainable current density in the electrodeposition from chloroaluminate ionic liquids strongly depends on the chemical rate constants for establishing the equilibrium Al 2 Cl 7 - + Cl - 2 AlCl 4 -. A high current (up to 3000 A m-2) was found for both high and low rate constants whereas a minimum current (200 A m-2) was found for intermediate rate constants due to kinetics and thermodynamics. The model is compared to experiments conducted in the ionic liquid AlCl3 - [C2mim]Cl (60/40 mol) where [C2mim]Cl is 1-ethyl-3-methylimidazolium chloride.

Electrodeposition of Al coatings from dimethylsulfone (DMSO 2)-AlCl3 baths with the addition of ZrCl4 was studied. Although pure Al coatings electrodeposited from the bath without ZrCl4 are lusterless, bright and smooth coatings were obtained when the ZrCl4 content in the baths was 0.005-0.015 mol per 10 mol DMSO2. The Zr content in the coatings varied up to 3.5 at% in proportion to the ZrCl4 content in the baths. The bright Al-Zr alloy coating showed high reflectance of 50-80% in the wavelength range of 450-1000 nm, whereas that of the matte pure Al coating was 10-20%. Morphological observations confirmed a reduction in the grain size of Al and surface leveling caused by the addition of ZrCl4 to the baths. Moreover, a strong 100 preferential orientation of Al crystals was observed for the bright coatings. The bright coating containing ～3.5 at% Zr had a higher corrosion potential by 0.1 V than the pure Al coating.

We investigated an electroless aluminum plating based on using AlCl3-1-ethyl-3-methylimidazolium chloride (AlCl3-EMIC) ionic liquid with diisobutyl aluminum hydride (DIBAH) as a liquid reducing agent. The plating film was analyzed by

Metastable induced electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) were used to study the interaction of nanocrystalline aluminium with oxygen and carbon monoxide, respectively. High resolution scanning electron microscopy (HRSEM) was used to investigate the morphology of the nanocrystalline aluminium films. These films were prepared by electrodeposition from the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide containing 1.6 Mol per litre AlCl3 in an argon filled glove box. Only a slight oxidation under exposure to oxygen and carbon monoxide was observed. After carbon monoxide dosage, no significant amount of carbon contamination was detected on the sample. These results indicate that the nanocrystalline aluminium is rather inert.

Aluminum electrodeposition from aprotic solutions of the organic complex KF·2Al(C2H5)3 on polycrystalline aluminum and vitreous carbon is described for potentiostatic and voltage pulse conditions. Near the equilibrium of the aluminum electrode, below currents of about -3 mA cm-2, electron transfer controls the deposition rate. Stationary polarizations over -0.1 V generate a material transport limitation which was controlled and eliminated by the rotating disk electrode technique. Extending the overvoltage to -0.1 to -0.3 V a slow chemical process characterized by a reaction current of ca -5 mA cm-2 precedes charge transfer. Above -0.3 and -0.7 V two further deposition mechanisms possibly involving slow chemical and crystallization steps were observed.

The co-deposition of Al and Zn on AZ91D magnesium alloy from a Lewis acidic aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl3-EMIC, with a molar ratio of 60:40) ionic liquid containing 1 wt% ZnCl2 at room temperature was studied. The effect of potential on the deposition rate, the microstructure and the chemical composition of the deposit was explored. The experimental results show that the simultaneous deposition of Al and Zn on Mg alloy can be achieved under properly controlled potential conditions. The deposition rate increased while the amount of Zn existing in the coating decreased with increasing negative deposition potential. In the ionic liquid studied, a uniform chemical composition of the coating was obtained when the deposition was performed at -0.2 V (vs. Al).

In this work, the co-reduction of La(III) and Al(III) ions on the Mo electrode was investigated in LiCl-KCl eutectic at 723-806 K. Cyclic voltammetry (CV), square wave voltammetry (SWV), and open-circuit chronopotentiometry (OCP) techniques were employed

Method for synthesis of nanodisperse yttrium-aluminum garnet powders activated with cerium and silicon ions was developed. The method is based on a combination of sol-gel synthesis and coprecipitation of hydroxides of the corresponding metals. The process modes were optimized and the structural, physicochemical, and spectral-luminescent characteristics of the samples obtained were studied.

In the present work, bulk amorphous and nanocrystalline Al83Fe17 alloys were obtained by consolidation of mechanically alloyed powders. Mechanical alloying of Al-17% Fe powder mixture yielded powder with an amorphous structure. Thermal behaviour of the milling product was examined using differential scanning calorimetry. This investigation revealed that the amorphous phase crystallised above 380 °C. The amorphous powder was compacted under a pressure of 7.7 GPa in different conditions: at 380 °C for 600 s and at 1000 °C for 180 s. Structural investigations of the bulk material revealed that the amorphous structure was retained after consolidation process applied at 380 °C. Compaction under high pressure at 1000 °C caused crystallisation of the amorphous phase and appearance of metastable nanocrystalline phases, different to those which crystallised during heating in the calorimeter under atmospheric pressure. The microhardness of the bulk amorphous sample is 760 HV0.2, whereas that of bulk nanocrystalline one is 630 HV0.2. The density of the bulk amorphous material is 3.505 g/cm3 and is ～3% lower than that of the nanocrystalline one. The open porosity of both consolidated materials is 0.4%. The results obtained show that the quality of compaction preserving amorphous structure as well as of the one yielding nanocrystalline structure is satisfactory and the products' microhardness is relatively high. The results also indicate that application of high pressure affects crystallisation of amorphous alloy influencing the phase composition of the products of this process.

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We have constructed a hermetically sealed high-temperature cell for an X-ray diffractometer which allows in situ identification of structural phase changes during the several thermal decomposition stages of sodium alanate materials. Comparing X-ray data with thermogravimetry measurements allows identification of phase changes that correlate with hydrogen release. Measurements made while uniformly ramping up the temperature of purified NaAlH4 indicate that all of the hydrogen release corresponds to the formation of Al or the formation and decomposition of the Na3AlH6 phase. The melting of the NaAlH4 phase does not correlate well with sample mass loss in the purified material. For as-received technically pure NaAlH4, hydrogen release lags both Al formation and the formation and decomposition of the Na3AlH6 phase. In ball-milled as-received NaAlH4 (ball-milled with diamond powder to achieve ～2 μm crystallite size) there is good correspondence between hydrogen release and either Al formation or the formation and decomposition of the Na3AlH6 phase, except that hydrogen release lags the phase changes by a few degrees. For purified NaAlH4 ball-milled in either a steel or tungsten carbide jar, there is a much smaller lag in hydrogen release. For Ti doped material, the phase changes to NaH are completed at the lowest temperature observed in any of the samples, 215°C, but the TGA measurements are not reliable because of mass loss from decomposition of the catalyst butoxide anion. Among these samples, the delay in hydrogen release does not correlate well with crystallite size; indicating that the delay is not due to hydrogen diffusion, but the delay is definitely decreased by ball milling or adding catalyst material or even impurities.

The chemical and electrochemical behavior of titanium was examined in the Lewis acidic aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl3-EtMeImCl) molten salt at 353.2 K. Dissolved Ti(II), as TiCl2, was stable in the 66.7-33.3% mole fraction (m/o) composition of this melt, but slowly disproportionated in the 60.0-40.0 m/o melt. At low current densities, the anodic oxidation of Ti(0) did not lead to dissolved. Ti(II), but to an insoluble passivating film of TiCl3. At high current densities or very positive potentials, Ti(0) was oxidized directly to Ti(IV); however, the electrogenerated Ti(IV) vaporized from the melt as TiCl4(g). As found by other researchers working in Lewis acidic AlCl3-NaCl, Ti(II) tended to form polymers as its concentration in the AlCl3-EtMeImCl melt was increased. The electrodeposition of Al-Ti alloys was investigated at Cu rotating disk and wire electrodes. Al-Ti alloys containing up to ～19% atomic fraction (a/o) titanium could be electrodeposited from saturated solutions of Ti(II) in the 66.7-33.3 m/o melt at low current densities, but the titanium content of these alloys decreased as the reduction current density was increased. The pitting potentials of these electrodeposited Al-Ti alloys exhibited a positive shift with increasing titanium content comparable to that observed for alloys prepared by sputter deposition.

We present a spectroscopic and microscopic study of nanoscale Al and Si films electrodeposited in water- and air-stable ionic liquids. The choice of cations for such ionic liquids has previously been shown to have a significant effect on the crystallite size of electrodeposited Al or Si films. We found that the deposits are generally uniform, dense, metallic bright, and adherent with crystallite sizes in the nanometer range. The nanocrystalline films were characterized using X-ray Photoelectron Spectroscopy (XPS) and High-Resolution Scanning Electron Microscopy (HRSEM). The XPS results show that the surface of both films is oxidized although the deposition was done in an inert gas glove box. Furthermore our results suggest that as a consequence of oxygen attack the nanoparticles are composed of a metallic core surrounded by a thin oxidic shell. Our XPS study also shows tliat neither the cation nor the anion of the ionic liquid is entrapped in the deposit. Thus, electrodeposition in ionic liquids delivers pure materials. by Oldenbourg Wissenschaftsverlag.

The lattice parameters of Al3BC have been measured up to 5 GPa at ambient temperature using energy-dispersive X-ray powder diffraction with synchrotron radiation. A fit to the experimental p-V data using Birch-Murnaghan equation of state gives values of the Al3BC bulk modulus 116(4) GPa and its first pressure derivative 9(2). In the 1.6-4.8 GPa range at temperatures above 1700 K Al3BC undergoes incongruent melting that results in the formation of Al3BC3, AlB2 and liquid aluminum.

A mechanochemical synthesis process has been used to synthesise aluminium nanoparticles. The aluminium is synthesised via a solid state chemical reaction which is initiated inside a ball mill at room temperature between either lithium (Li) or sodium (Na)

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Constant current and pulsed current electrodeposition of aluminium nano-rods, for use as three-dimensional (3D) Li-ion micro-battery current collectors, have been studied using an ionic liquid electrolyte (1-ethyl-3-methylimidazolium chloride/aluminium chloride) and a template consisting of a commercial alumina membrane. It is shown that the homogeneity of the height of the rods can be improved significantly by inclusion of a short (i.e. 50 ms) potential pulse prior to the controlled current deposition step. The latter potential step increased the number of aluminium nuclei on the aluminium substrate and the best results were obtained for a potential of -0.9 V vs. Al/Al3+. The obtained nanostructured surfaces, which were characterized using electron microscopy and X-ray diffraction, consisted of parallel aligned aluminium nano-rods homogeneously distributed over the entire surface of the substrate. A narrower height distribution for the rods was obtained using a pulsed galvanostatic approach then when using a constant current, most likely due to the less favourable diffusion conditions in the latter case. The results also indicate that depletion and iR drop effects within the nano-pores result in a more homogeneous height distribution. It is concluded that the height distribution of the nano-rods is controlled by a combination of the nucleation probability in each pore at the start of the experiment, and the homogeneity of the diameters of the pores within the commercial alumina membranes employed as the electrodeposition template.

The thermal stability of Al3BC3 powder was analyzed. Nearly X-ray-pure Al3BC3 powder was obtained through the calcination of the aluminum, B4C, and carbon mixture at 1800°C in Ar. In contrast to the f

Despite the common use of salens and hydroxyquinolines as therapeutic and bioactive agents, their metal complexes are still under development. Here, we report the synthesis of novel mixed-ligand metal complexes (MSQ) comprising salen (S), derived from (2,2′-{1,2-ethanediylbis [nitrilo(E) methylylidene]}diphenol, and 8-hydroxyquinoline (Q) with Co(II), Ni(II), Cd(II), Al(III), and La(III). The structures and properties of these MSQ metal complexes were investigated using molar conductivity, melting point, FTIR,1H NMR,13C NMR, UV–VIS, mass spectra, and thermal analysis. Quantum calculation, analytical, and experimental measurements seem to suggest the proposed structure of the compounds and its uncommon monobasic tridentate binding mode of salen via phenolic oxygen, azomethine group, and the NH group. The general molecular formula of MSQ metal complexes is [M(S)(Q)(H2O)] for M (II) = Co, Ni, and Cd or [M(S)(Q)(Cl)] and [M(S)(Q)(H2O)]Cl for M(III) = La and Al, respectively. Importantly, all prepared metal complexes were evaluated for their antimicrobial and anticancer activities. The metal complexes exhibited high cytotoxic potency against human breast cancer (MDA-MB231) and liver cancer (Hep-G2) cell lines. Among all MSQ metal complexes, CoSQ and LaSQ produced IC50 values (1.49 and 1.95 μM, respectively) that were comparable to that of cisplatin (1.55 μM) against Hep-G2 cells, whereas CdSQ and LaSQ had best potency against MDA-MB231 with IC50 values of 1.95 and 1.43 μM, respectively. Furthermore, the metal complexes exhibited significant antimicrobial activities against a wide spectrum of both Gram-positive and-negative bacterial and fungal strains. The antibacterial and antifungal efficacies for the MSQ metal complexes, the free S and Q ligands, and the standard drugs gentamycin and ketoconazole decreased in the order AlSQ > LaSQ > CdSQ > gentamycin > NiSQ > CoSQ > Q > S for antibacterial activity, and for antifungal activity followed the trend of LaSQ > AlSQ > CdSQ > ketoconazole > NiSQ > CoSQ > Q > S. Molecular docking studies were performed to investigate the binding of the synthesized compounds with breast cancer oxidoreductase (PDB ID: 3HB5). According to the data obtained, the most probable coordination geometry is octahedral for all the metal complexes. The molecular and electronic structures of the metal complexes were optimized theoretically, and their quantum chemical parameters were calculated. PXRD results for the Cd(II) and La(III) metal complexes indicated that they were crystalline in nature.

Dehydrogenation processes of α- and γ-AlH3 were investigated by in situ transmission electron microscopy observations. The relationship between Al2O3 thickness and dehydrogenation kinetics was also clarified. The initial s

The sorption capacity and kinetics of mechanically activated binary mixtures of Mg with nine different metals (Al, Cu, Fe, Mn, Mo, Sn, Ti, Zn, Zr) have been studied to determine whether these metals act as catalyzing/destabilizing agents in formation/decomposition of Mg hydrides. Identification of crystalline phases before and after the absorption/desorption processes assists our understanding of the different behaviors displayed by the studied compounds. Cu, Al and Zn take active part in Mg hydrogenation/dehydrogenation, but only the addition of Cu is actually effective in MgH2 destabilization, leading to a substantial decrease of the desorption temperature of this phase (down to 270 °C), and to an improved desorption kinetics. With the other metals, the hydrogen release usually occurs at a significant rate only above 320 °C and the kinetics of the absorption/desorption processes are slower than in the Mg/MgH2 system.

Powders of both commercial atomized spherical Al-Mg alloy and mechanically alloyed Al-Mg were oxidized in oxygen using thermo-gravimetry (TG). For both powders, the Al/Mg mass ratio was equal to 1. Fully and partially reacted powders were recovered and characterized using scanning electron microscopy and x-ray diffraction. Voids grow within oxidized alloy particles for both atomized and mechanically alloyed powders. Results were interpreted accounting for the measured particle size distribution for the spherical powder and distributing the TG-measured weight gain among the individual particle size bins. The reaction interfaces were always located at the internal surface of the oxide shell as determined by matching the oxidation dynamics for particles with the same sizes but belonging to powders with different particle size distributions. Thus, the reaction is always rate limited by inward diffusion of oxygen ions through the growing oxide shell. Two oxidation stages were identified for both materials. Both Al and Mg oxidize during both observed oxidation stages. The second oxidation stage is caused by formation of the spinel phase, most likely occurring at a threshold temperature. In the present measurements, the step in the oxidation rate, or switch between the oxidation stages, occurs when the oxide shell grows above a certain thickness of approximately 1.5 μm. The apparent activation energy during the first oxidation stage energy changes during the first oxidation stage suggesting that more than one reaction occur in parallel, e.g., causing formation of MgO and amorphous alumina. For the second oxidation step, controlled by diffusion of oxygen through spinel layer, the activation energy remains nearly constant around 185 kJ/mol.

The reaction of (C5H4tBu2)2Sm with AlH3 in ether or (C5H4tBu2)2Sm*THF with AlH3 in THF in the presence of excess of TMEDA and pentane inolves the oxidation of Sm(2+) to Sm(3+), partial loss of Cp''-ligands and formation of the octanuclear complex Cp5''Sm4(AlH4)3*2Me2NC2H4NMe2, the cyclic metal core of which resembles a sitting frog.Atoms Sm1, Sm3 and Sm4 are coordinated with one Cp''-ligand each, while Sm2 is bonded with two Cp''-ligands.All metals of the complex are bonded by μ2- and μ3-bridging hydrogens.

UV irradiation effects on Al chemical vapor deposition on titanium nitride (TiN) was investigated by using dimethylaluminum hydride at 150°C. Al films grew thermally at a rate of 6.3 nm/min, while the UV light generated by a deuterium lamp reduced the rate to 5.2 nm/min. When TiN surfaces were oxidized, Al films started to grow only under UV irradiation. Using x-ray photoelectron spectroscopy (XPS), we showed that the adsorbates formed on the oxidized surfaces could be dissociated only when the UV light was irradiated. The XPS results also suggested involvement of photoinduced desorption in reducing the growth rate.

The reactions of the intermetallic compounds Sc2Al and Sc 2Ni with hydrogen have been investigated. The results demonstrate that Sc2Ni reacts with hydrogen even at room temperature, to form amorphous Sc2NiH5. The reaction is irreversible at room temperature. Vacuum extraction of hydrogen between room temperature and 900°C leads to partial decomposition of Sc2NiH5 and the formation of crystalline ScH2 and ScNi2. Sc 2Al is nonreactive with hydrogen at room temperature. Heating at a hydrogen pressure of 5 MPa leads to Sc2Al hydrogenolysis starting at 225°C and the formation of ScH2 and metallic Al. Pleiades Publishing, Inc., 2006.

The X-ray diffraction analysis of hydrogenated Mg-30Al magnesium alloy was used to determine the effect hydrogen on phase changes and lattice parameters as well as hydride formation in the investigated alloy. The results of XRD analysis showed that the β-

Aluminum electrocrystallization is studied by means of electrochemical impedance spectroscopy (EIS). A model based on random birth and deterministic growth of monolayers is proposed, in which the edges are assumed to follow a propagation law. The high frequency impedance data show charge transfer reaction of AlCl4- reduction while the low frequency features signifies the growth mode of deposits. The inductive response observed in the course of polycrystalline deposition reflects the activation of electrode area while a capacitive loop appears in regular growth. Parameters of impedance model in this system can be calculated from the fitting of experimental data to the Faradaic impedance function derived theoretically. The physical parameters of this function are analyzed by means of the dependence of simulated EIS spectra on kinetic parameters.

In order to investigate an alternative process for the production of primary aluminum via a sulfide intermediate, the electrochemical behavior of Al2 S3 in molten salt has been studied on a laboratory scale. The effects of electrolyte composition, temperature, and cell design on the cell performance have been investigated. Temperature and cryolite addition have positive effects on the current density. Increasing the anode-to-cathode surface area (closer to unity) and shortening the interelectrode distance lead to higher current density. It is concluded that the electrolytic process is governed by the ohmic drop, caused mainly by the sulfur bubbles at the anode.

The electrochemical behavior of the rotating aluminum disc electrode in LiAlH4/tetrahydrofuran (THF)-toluene solutions was studied. The kinetic parameters controlling the electrode process were investigated. The effect of concentration of LiAlH

The effects of various additives, including alkali metal chlorides, rare earth chlorides, small organic molecules, and surfactants on the electrodeposition of aluminium were investigated. The analytical techniques of cyclic voltammetry, potentiostatic coulometry, scanning electron microscope, and X-ray diffraction were applied to determine the speciation, morphology, and nanocrystallinity. It was found that additives significantly influence the morphology and grain parameters of the aluminium deposits. Inorganic additives and macromolecular surfactants play a prominent role in altering the speciation of aluminium. Small organic molecules (including surfactants) with simple structures have almost no effect on the aluminium separation process, but have a role in densification and homogenisation. In addition, the grain size can be adjusted after adding various additives, and then nanocrystallinity can be achieved. In conclusion, the effect of additive on the aluminium deposit can be predicted by cyclic voltammetry, which is a clue for smart-design on technological conditions of aluminium electrodeposition. CSIRO 2012.

Two types of alumina-based ceramics, pure solid-state sintered (SSS) alumina ceramics, and a liquid phase sintered (LPS) alumina were corrosion tested under both static and quasi-dynamic conditions in 0.5M NaCl solution and in deionized water reference medium at the temperature of 290°C. Static tests were also performed at 150° and 200°C in order to obtain the data for determination of kinetic parameters, and for calculation of the activation energies. The apparent activation energies of dissolution of the LPS alumina in deionized water and in 0.5M NaCl solution were identical and ranged around 49 kJ/mol. The SSS alumina ceramics corroded by grain-boundary attack and slow dissolution of alumina matrix grains, and the corrosion rates were negligible in both corrosion media. The LPS alumina, corroded by preferential attack and dissolution of calcium aluminosilicate grain-boundary glass. The alumina matrix remained relatively intact. The dissolution was markedly faster than in the SSS alumina. The rates of dissolution were found to be temperature dependent, but no influence of the corrosion medium was observed.

Polycrystalline LiAlH4 transforms into polycrystalline Li3AlH6 and Al during short time.(5 min) ball-milling with 3 mol% TiCl4 at room temperature; solid-state rearrangement of tetrahedral [AlH4]

The electrodeposition of aluminum on the atomically smooth nitrogen-incorporated tetrahedral amorphous carbon (taC:N) electrode in ambient temperature AlCl3/EMIC chloroaluminate melts has been interpreted using a prior model of three-dimensional diffusion controlled nucleation and growth. Aluminum requires an unusually high overpotential for nucleation on taC:N because of the low density of intrinsic active sites, which act as critical nuclei during the initial stage of deposition. The current-time characteristics of nucleation on taC:N show a strong dependency on overpotential. Generation of additional, overpotential-induced active sites imposes a partial progressive nature on the overall nucleation process, resulting in a slight deviation from the limiting behavior of an ideal instantaneous nucleation model.

The authors have developed a new deposition system, magnetron-plasma CVD (MPCVD), allowing the practical application of metal organic CVD of Al films. With this system, it has been found that the plasma chemical recation is confined to the surface region of the substrate by an applied planar magnetic field. The fundamental parameters for the MPCVD and the characterization of deposited Al film were investigated. The low temperature deposition was performed below 100 degree C. A hillock-free Al film with a resistivity of 3. 8 multiplied by 10** minus **6 OMEGA -cm was obtained.

Ionic liquids (ILs) are solvents of interest for applications such as electroplating, winning, and refining of metals. In this study, the conductivity of the Al Cl3 -trihexyl(tetradecyl) phosphonium chloride ([P14,6,6,6] Cl) system was characterized over a wide range of Al Cl3 concentration and temperature. Cyclic voltammetry was used to determine the electrochemical window of the neat IL using a Pt substrate. The anodic and cathodic potentiodynamic polarization behavior of Al was measured in Al Cl3 - [P14,6,6,6] Cl at an Al Cl3 concentration of 0.67 mol fraction (XAl Cl3). Aluminum was electrodeposited at a constant potential over a range of potentials (0.3-0.75 V); the deposit morphology, current efficiency, and power consumption are provided. The presence and effects of impurities such as H2 O and HCl in the ionic liquid are also addressed.

First-principles modeling, experimental, and thermodynamic methodologies were integrated to facilitate a fundamentally guided investigation of quaternary complex hydride compounds within the bialkali Na-Li-Al-H hydrogen storage system. The integrated approach has broad utility for the discovery, understanding, and optimization of solid-state chemical systems. Density functional theory ground-state minimizations, low-temperature powder neutron diffraction, and low-temperature synchrotron X-ray diffraction were coupled to refine the crystallographic structures for various low-temperature distorted Na2LiAlH6 allotropes. Direct method lattice dynamics were used to identify a stable Na2-LiAlH6 allotrope for thermodynamic property predictions. The results were interpreted to propose transformation pathways between this allotrope and the less stable cubic allotrope observed at room temperature. The calculated bialkali dissociation pressure relationships were compared with those determined from pressure-composition-isotherm experiments to validate the predicted thermodynamic properties. These predictions enabled computational thermodynamic modeling of Na2LiAlH6 and competing lower order phases within the Na-Li-Al-H system over a wide of temperature and pressure conditions. The predictions were substantiated by experimental observations of varying Na2LiAlH6 dehydrogenation behavior with temperature. The modeling was used to identify the most favorable reaction pathways and equilibrium products for H discharge/recharge in the Na-Li-Al-H system, and to design conditions that maximize the theoretical hydrogen reversibility within the Na-Li-Al-H system.

Mechanical alloying of magnesium metal powders with hydrogen in specialized hydrogen ball mills can be used as a direct route for mechanochemical synthesis of emerging chemical hydrides and hydride mixtures for advanced solid-state hydrogen storage. In the 2Mg-Fe system, we have successfully synthesized the ternary complex hydride Mg2FeH6 in a mixture with nanometric Fe particles. The mixture of complex magnesium-iron hydride and nano-iron released 3-4 wt.%H2 in a thermally programmed desorption experiment at the range 285-295 °C. Milling of the Mg-2Al powder mixture revealed a strong competition between formation of the Al(Mg) solid solution and the β-MgH2 hydride. The former decomposes upon longer milling as the Mg atoms react with hydrogen to form the hydride phase, and drive the Al out of the solid solution. The mixture of magnesium dihydride and nano-aluminum released 2.1 wt.%H2 in the temperature range 329-340 °C in the differential scanning calorimetry experiment. The formation of MgH2 was suppressed in the Mg-B system; instead, a hydrogenated amorphous phase (Mg,B)Hx, was formed in a mixture with nanometric MgB2. Annealing of the hydrogen-stabilized amorphous mixture produced crystalline MgB2.

The chlorination of Al-Cu alloys is investigated by thermogravimetry, X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and energy dispersive X-ray fluorescence, between 200 and 500 °C. The starting temperature for the chlorination of selected alloys is determined. Results indicate that the reactivity of the alloys is different from that of the pure metals. Analysis of the reaction products reveals that there are interactions between the different chlorides formed. These interactions lead to an enhancement in the copper chlorides volatilization and the formation of well-developed crystals of CuCl2 instead of the mixture of CuCl2 and CuCl that is obtained in the chlorination of pure copper. A schematic diagram that describes the chlorination mechanisms for the pure metals and AlCu alloys is presented.

Aluminium atom association reactions with the title ethers in the gase phase are investigated by time-resolved fluorescence excitation of ground-state Al atoms following pulsed visible laser photolysis of trimethylaluminium in a gas cell.Ar buffer gas pressure effects on the reaction rates are observed and interpreted in terms of collision complex formation in termolecular reactions.The limiting high Ar pressure bimolecular rate constants approach gas kinetic values, implying small or negligible activation energy barriers and large Arrhenius preexponential factors for these reactions.For each of dimethyl ether (DME), diethyl ether (DEE), and tetrahydrofuran (THF), an equilibrium is observed between free Al atoms and bound Al atom-ether complexes.Equilibrium constants for the dissociation reaction are obtained through analysis of kinetic data at different reactant pressures.Binding energies are derived from observations of the temperature dependence of the equilibrium constant in the range 5-35 deg C for DME and 5-30.5 deg C for DEE or through estimation of the standard entropy change for the dissociation of all three ether complexes in conjunction with measurements of the equilibrium constant for dissociation at room temperature.Evidence is presented which indicates that Al atoms form monoligand complexes with these three ethers.Al atom binding energies (kcal mol-1 are reported for Al-DME (9.2 +/- 0.6) and Al-DEE (9.2 +/- 1.2).The binding energy for Al-THF is estimated at 10.8 kcal mol-1 based upon the room-temperature equilibrium constant.Trends in binding energy and bonding mechanisms are discussed with regard to known and calculated properties of metal atom complexes with water and Lewis acid complexes of ethers.

The hydrogenation behavior of the polar intermetallic systems AeE 2 (Ae = Ca, Sr, Ba; E = Al, Ga, In) has been investigated systematically and afforded the new hydrides SrGa2H2 and BaGa2H2. The structure of these hydrides was characterized by X-ray powder diffraction and neutron diffraction of the corresponding deuterides. Both compounds are isostructural to previously discovered SrAI 2H2 (space group P3m1, Z = 1, SrGa2H 2/D2: a = 4.4010(4)74.3932(8) A, c = 4.7109(4)/4.699(1) A; BaGa2H2/D2: a = 4.5334(6)/4.5286(5) A, c = 4.9069(9)/4.8991(9) A). The three hydrides SrAI2H2, SrGa2H2, and BaGa2H2 decompose at around 300 °C at atmospheric pressure. First-principles electronic structure calculations reveal that H is unambiguously part of a two-dimensional polyanion [E2H 2]2- in which each E atom is tetrahedrally coordinated by three additional E atoms and H. The compounds AeE2H2 are classified as polyanionic hydrides. The peculiar feature of polyanionic hydrides is the incorporation of H in a polymeric anion where it acts as a terminating ligand. Polyanionic hydrides provide unprecedented arrangements with both E-E and E-H bonds. The hydrogenation of AeE2 to AeE2H 2 takes place at low reaction temperatures (around 200 °C), which suggests that the polyanion of the polar intermetallics ([E2] 2-) is employed as precursor.

Because aluminum is a less-noble metal which has the standard electrode potential of -1.676 V vs normal hydrogen electrode, it is impossible to obtain the electrodeposition of aluminum from an aqueous solution. No one has reported an electroless plating method of aluminum. We succeeded in demonstrating the electroless plating of aluminum from a room-temperature ionic liquid (RTIL). It was found from measurements of inductively coupled plasma, X-ray diffraction, scanning electron microscopy (SEM), SEM-energy-dispersive X-ray analysis, and glow discharge optical emission spectroscopy that dense, smooth, and pure aluminum plating was obtained from the RTIL by the electroless plating method. Moreover, the reaction mechanism of the electroless plating of aluminum from the RTIL electrolyte was electrochemically analyzed.

Na3 Al H6 can be directly formed by mechanical milling NaHAl with Ti F3 under hydrogen atmosphere. The hydrogenation fraction of NaH increases with increasing the milling time, and reaches up to 0.61 after 20 h milling. Thus-formed Na3 Al H6 exhibits unexpected polymorphic transformation and decomposition behaviors. This, together with the unusual hydrogen storage performance of the mechanically prepared materials, provides us a suggestive perspective to probe the favorable modification of the thermodynamics of Na3 Al H6 and nature of active Ti-species in Ti-doped NaAl H4.

A new method to stabilize and functionalize surfaces for surface-enhanced Raman spectroscopy (SERS) is demonstrated. Atomic layer deposition (ALD) is used to deposit a sub-1-nm alumina layer on silver film-over-nanosphere (AgFON) substrates. The resulting overlayer maintains and stabilizes the SERS activity of the underlying silver while presenting the surface chemistry of the alumina overlayer, a commonly used polar adsorbent in chromatographic separations. The relative affinity of analytes for alumina-modified AgFON substrates can be determined by their polarity. On the basis of SERS measurements, dipicolinic acid displays the strongest binding to the ALD alumina-modified AgFON among a set of pyridine derivatives with varying polarity. This strong affinity for carboxylate groups makes the SERS substrate an ideal candidate for bacillus spores detection using the dipicolinate biomarker. The SERS signal from extracted dipicolinate was measured over the spore concentration range 10 -14-10-12 M to determine the saturation binding capacity of the alumina-modified AgFON surface. The adsorption constant was determined to be Kspore = 9.0 × 1013 M-1. A 10-s data collection time is capable of achieving a limit of detection of ～1.4 × 103 spores. The shelf life of prefabricated substrates is at least 9 months prior to use. In comparison to the bare AgFON substrates, the ALD-modified AgFON substrates demonstrate twice the sensitivity with 6 times shorter data acquisition time and 7 times longer temporal stability. ALD expands the palette of available chemical methods to functionalize SERS substrates, which will enable improved and diverse chemical control over the nature of analyte-surface binding for biomedical, homeland security, and environmental applications.

Deposition of aluminum film from DMEAA in the temperature range of 100-300°C has been studied. In this temperature range, there is a maximum deposition rate at around 150°C. The film deposited at 190°C has elongated blocklike grain shapes, which are ～600 nm in width and 930 nm in length. Grains in the film deposited at 150°C showed an equiaxed structure with grain size in the range of 100-300 nm in a film with 600 nm thickness. Aluminum oxide particle inclusion was observed especially at high deposition temperature. Plausible reaction pathways of DMEAA dissociation were suggested to explain the experimental observations.

The hydride Sr2AlH7 was synthesized by ball milling of the alloy consisting of Sr and Al (2:1) under hydrogen at 150 rpm for 10 h followed by hydrogenation or sintering at 533 K for 2 days. The yield of Sr 2AlH7 in the hydrogenated product was 66 wt.%, which is larger than that in the sintered product. However, the mass fraction of Al in the milled samples decreased largely when the Sr2Al alloy was milled at 300 rpm for 50 h or longer. In such a case, the Sr2AlH7 hydride cannot be obtained during the subsequent hydrogenation.

Abstract: The decomposition of aluminum hydride complexes with trimethylamine andN-heterocyclic carbene—1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene was studied by a statictensimetric method with a membrane null-manometer. TheAlH3·NMe3 complex passes intovapor in the form of monomeric molecules and in unsaturated vapor slowlydecomposes at 70?80°С into solid aluminum, gaseous trimethylamine, and hydrogen.The decomposition is accompanied by an induction period, the duration of whichdecreases as temperature increases. The AlH3 complex withcarbene slowly decomposes at 170?200°С with a rate practically independent oftemperature.

With the isolation of Cp3tAl (1), the first monomeric Cp-based Al(i) species could be realized in a pure form via a three-step reaction sequence (salt elimination/adduct formation/adduct cleavage) starting from readily available AlBr3. Due to its monomeric structure, reactions involving 1 were found to proceed more selectively, faster, and under milder conditions than for tetrameric (Cp*Al)4. Thus, 1 readily formed simple Lewis acid-base adducts with tBuAlCl2 (6) and AlBr3 (7), reactions that before have always been interfered with by the presence of aluminum halide bonds. In addition, the 2?:?1 reaction of 1 with AlBr3 enabled the realization of the very rare trialuminum adduct species 8. 1 also reacted rapidly with N2O and PhN3 at room temperature to afford Al3O3 and Al2N2 heterocycles 9 and 10, respectively. With the structural characterization of products 4 and 5, the reaction of monovalent 1 with Cp3tAlBr2 (2) provided the first experimental evidence for the concept of valence isomerism between dialanes and their Al(i)/Al(iii) Lewis adducts.

Abstract: A 200-micron powder of γ-Mg17Al12 was reacted with hydrogen and ammonia at temperatures in the range 20–500°C with the goal to determine optimal hydrogenation parameters for this intermetallic compound as a potential hydrogen storage material. Direct hydriding of the intermetallic compound was found to occur at 390°C, but was accompanied by decomposition to a mixture of magnesium hydride with aluminum containing 4 wt % hydrogen. The hydriding of the intermetallic compound by ammonia was also accompanied by the appearance of magnesium hydride in the reaction product, but at 300°C. The hydrogen capacity of the products of reaction between the intermetallic compound and ammonia at 350°C was 3.9 wt % hydrogen. The product of ammonia treatment of the intermetallic compound Mg17Al12 at 450–500°C was a mixture of aluminum with magnesium nitride.

Abstract: Aluminum hydride is particularly attractive as a hydrogen storage material due to its high hydrogen volumetric capacity and relatively low hydrogen desorption temperature. However, the properties of nanoscale α?AlH3 particles are not studied completely due to the difficulties in their synthesis. In this work, we report the synthesis of nanoscale α-AlH3 based on a modified method, together with its activation energy measurements and hydrogen release kinetics. We have discovered that the dehydrogenation activation energy (93.23 kJ/mol) of nanoscale α-AlH3 is remarkably lower than that of micrometer-sized α-AlH3, which further expand practical application of AlH3. Moreover, we demonstrate that the decomposition kinetics of nanoscale α-AlH3 is controlled by nucleation and growth of the aluminum phase in three dimensions. This work first time provides systematic investigation of thermodynamic properties of nano-scale AlH3, which paves the way for its practical applications.

The invention relates to powdery, highly reactive alkali and alkaline earth hydride compounds, and to mixtures with elements of the third main group of the periodic table of elements (PTE) and to the preparation thereof by reacting alkali or alkaline earth metals in the presence of finely dispersed metals or compounds of the third main group of the PTE, wherein the latter have one or more hydride ligands or said hydride ligands are converted in situ, under the prevailing reaction conditions, i.e., in the presence of hydrogen gas or another H source, into hydride species, and to the use thereof for the preparation of complex hydrides and organometallic compounds.

Mixed alkali alanates LixNa3-xAlH6 have been successfully synthesized by means of grinding mixtures of Li3AlH6 and Na3AlH6 in specific molar ratios. Non-stoichiometric Lix/

The hydrogen storage performance of a 4MgH2-LiAlH4 composite system was greatly improved by adding TiH2. The temperature-programmed release curve of the 4MgH2-LiAlH4-TiH2 composite reflecte

The structures adopted by a range of complexes AlH3·nL, (n = 1 or 2), have been explored in detail to identify the factors that determine the value of n, and whether a monomeric or dimeric arrangement is preferred for the 1 : 1 complexes. Single-crystal X-ray diffraction, vibrational and NMR spectroscopies, and thermal analysis data have been collected, DFT calculations have been performed for AlH3·nL species, and pKa values have been collated for a series of amine and phosphine ligands L. The pKa of the ligand L exerts an important influence on the type of complex formed: as the basicity of L increases, a monomeric structure is favoured over a dimeric arrangement. Dimeric amine complexes form if pKa a > 9.99. The steric requirements of L also influence the structural preference: bulky ligands with large cone angles (>163°) tend to favour formation of monomers, while smaller cone angles (3·NMe 2Et, AlH3·NMe3 and AlH 3·nEt2O. The Royal Society of Chemistry 2013.

The dehydrogenation performance and mechanism of the synthesized NaAlH 4-Mg(AlH4)2 powders were investigated by performing thermogravimetric analysis and in situ synchrotron X-ray diffraction analysis. NaAlH4 not only facilitates the first step dehydrogenation of Mg(AlH4)2 in lowering its initial dehydrogenation temperature but also increases the total amount of H2 released. Besides, MgH2 and/or Al phases, the products of the first step dehydrogenation reaction, play a catalytic role in lowering the initial dehydrogenation temperature of NaAlH4. The synthesized NaAlH4-Mg(AlH4) 2 mixture has an initial dehydrogenation temperature as low as 120 °C, and is able to release 5.35 wt% H2 below 350 °C. The self-catalytic dehydrogenation behavior of the NaAlH4-Mg(AlH4) 2 mixture was elaborated in this work with the aid of in situ synchrotron XRD.

The constitution of the Al-rich part of the Al Pt alloy system is revised. Apart from the previously reported equilibrium Al4Pt, Al21Pt8 and Al2Pt phases, a complex intermetallic was revealed at 75- 76 at.% Al between 801 and 915 °C. Its structure determined by electron diffraction is orthorhombic (Bmmb, a = 1.983, b = 1.636 and c = 1.422 nm).

The Zintl compound CaAl2Si2 is peritectically decomposed to a mixture of Ca2Al3Si4 and aluminum metal at temperatures above 600 °C under a pressure of 5 GPa. The new ternary compound Ca2Al3Sl4 crystalizes with the space group Cmc21 and the lattice parameters a=5.8846(8), b=14.973(1), and c=7.7966(5) A. The structure is composed of aluminum silicide framework [Al3Si4] and layer structured [Ca 2] network interpenetrating with each other. The electron probe microanalysis (EPMA) shows the formation of solid solutions Ca 2Al3-xSi4+x (x2] sub-network is isomorphous with black phosphorus. The new ternary compound shows superconductivity with a transition temperature (T c) of 6.4 K. The band structure calculation suggests that the superconductivity should occur through the conduction bands mainly composed of 3p orbitals of the aluminum silicide framework.

Compounds Cp*AlH2 (1) and Cp*2AlH (2) reductively eliminate Cp*H in benzene or toluene under reflux conditions to give Al(s) and AlCp*, respectively. The Royal Society of Chemistry 2013.

The Zintl compound CaAl2Si2 peritectically decomposes to a new ternary cubic Laves phase Ca(Al,Si)2 and an Al-Si eutectic at temperatures above 750 C under a pressure of 13 GPa. The ternary Laves phase compound can also be prepared as solid solutions Ca(Al1-xSi x)2 (0.35 ≤ x ≤ 0.75) directly from the ternary mixtures under high-pressure and high-temperature conditions. The cubic Laves phase structure can be regarded as a type of clathrate compound composed of face-sharing truncated tetrahedral cages with Ca atoms at the center, Ca at Al,Si)12. The compound with a stoichiometric composition CaAlSi exhibits superconductivity with a transition temperature of 2.6 K. This is the first superconducting Laves phase compound composed solely of commonly found elements.

A new inorganic material was used to produce hydrogen in situ by contact with water for reduction of unsaturated hydrocarbons. Phenylacetylene reduction into styrene and ethylbenzene was chosen as a model reduction reaction. We show that a fine control over the reaction yield and selectivity can be obtained by controlling the hydrogen release and such parameters of the synthesis as the temperature, water content and the speed of stirring. We found that the largest amount of water at 80 C and vigorous stirring result in the highest yield and selectivity of the reaction. An alternative way of reaction control is suggested as compared to a conventional way of a catalyst inhibition. The new possibility of the reaction control may be of a wide interest for the laboratory synthesis for a good number of hydrogenation reactions.

High surface area nanosized α-alumina has been obtained by thermally treating a sol-gel-derived mesophase at 1200 C; the mesophase was synthesized by a sol-gel route involving evaporation induced self-assembly (EISA) of a hydrolyzed gel from Al-tri-sec-butoxide in s-BuOH in the presence of a nonionic surfactant (EO20PO70EO20), HCl as catalyst, and water (H2O/Al = 6). The activated material renders moderate surface areas of about 8.4-10 m2 g-1, associated with significant crystallite coarsening. The key aspect to produce smaller crystallites is making the mesophase more resistant to coarsening. This was achieved by enhancing the condensation step by treating the hydrolyzed gel with tetrabutyl ammonium hydroxide (TBAOH) before evaporation. The characteristics of the mesophase indicate condensation of the primary particles with less AlO5 unsaturated sites, at the expense of a lower solid yield due to small crystallites dissolution. The activated TBAOH condensed EISA material is composed of α-alumina aggregated crystallites of about 60-100 nm, and the material possesses surface areas ranging from 16 to 24 m2 g -1 due to the improved resistance to coarsening. At least two aspects are suggested to play a role in this. The worm-hole morphology of the mesophase aggregates yields high particle coordination, which favors densification rather than coarsening. Furthermore, the decrease of the AlO5 defect sites by the TBAOH condensation makes the mesophase less reactive and consequently more resistant to coarsening.

In this paper we show that nanocrystalline aluminium can be electrodeposited from the ionic liquid 1-butyl-1-methylpyrrolidinium chloride ([Py1,4]Cl/AlCl3) (40/60 mol%). The study comprises electrochemical experiments such as cyclic

We report on the size effects of nano-patterned Si(1 1 1) substrates on the selective growth of GaN nanowires (NWs) using metal organic chemical vapor deposition. The nano-patterns on Si(1 1 1) substrates were fabricated by etching process of Au nano-droplets. The size of nano-patterns fabricated on Si(1 1 1) substrates were corresponding to size of Au nano-droplets, and the diameter of GaN NWs grown on nano-patterns was similar to the size of nano-pattern. Dense and well-oriented GaN NWs were grown on Si(1 1 1) substrates corresponding to the nano-patterns with an average diameter of about 50 nm. However, only a few GaN bulk grains, and mixed phase of a few NWs and bulk crystal of GaN were grown on the nano-patterned Si(1 1 1) having too small and large diameter, respectively, compare to the nano-patterns with diameter of 50 nm. Our results suggested that the selective growth of GaN NWs is strongly affected by the size of nano-patterns and its related mechanism.

Various metal nanoparticles including base metal were produced by a brief accelerated electron beam irradiation of 1-alkyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide room-temperature ionic liquid without a stabilizing agent, which is usually employed so as to prevent aggregation.

Electrodeposition of aluminum from an AlCl3-EMIC ionic liquid with or without the addition of saturated LaCl3 was carried out by both direct- and pulse-current plating methods. The effects of various parameters, including current density, pulse frequency, current on/off duration (ton and toff), and temperature, on deposit morphology and crystal size were investigated. Deposits prepared by pulse-current plating gave a brighter and flatter surface than those prepared by direct-current plating at appropriate pulse current parameters. Temperature and pulse-current frequency (toff) were shown to significantly affect deposit morphology. Coalescence of grains during toff periods in the pulse current plating was observed, especially at temperatures above 60 °C. Increasing the temperature from 25 to 90 °C caused an increase in deposit grain size and resulted in a change of grain shapes from a small sphere-like form to a feather-like form. As a result, the adhesion of the deposited aluminum to the substrate was lowered. Smaller grain sizes and well-adhered deposits were achieved at lower temperatures. For example, deposition at 25 °C resulted in the smallest crystal size of about 0.3 μm under the conditions of t on = 80 ms, toff = 20 ms, and i = 8 mA/cm2. Furthermore, the addition of LaCl3 to the melt at 60 °C effectively reduced the porosity and improved compactness of deposits.

In this paper we report on recent results from our group, namely on the interface ionic liquid/electrode, plasma electrochemistry and electrodeposition of selenium and of macroporous structures. Ionic liquids show an interesting and liquid dependent surface chemistry: in some liquids the long range "herringbone" superstructure of Au(1 1 1) is visible, in others it is not. Glow discharge plasmas can be employed as a contact free electrode to make nanoparticles in solutions, e.g. nanoparticles of germanium. Selenium can be electrodeposited from ionic liquids under environmental conditions in an open cell and both the red and the grey phases of selenium are feasible. With the help of self organized opal structures of polystyrene spheres macroporous materials of Ag, Al and conducting polymers can be made. The prospects and limits of ionic liquids in surface electrochemistry and electrodeposition are shortly discussed.

The addition of a simple amide to AlCl3 causes the formation of a liquid of the form [AlCl2·nAmide]+ AlCl 4-. The material thus produced is liquid over a wide temperature range, is relatively insensitive to water and has the properties of an ionic liquid. This ionic liquid is shown to be a suitable medium for the acetylation of ferrocene and the electrodeposition of aluminium and demonstrated that quaternary ammonium cations are not always needed to form ionic liquids.

CeAl4-doped Ca(AlH4)2 was synthesized by reactive ball-milling NaH/Al and CaCl2 with a few moles of CeAl 4 catalyst under hydrogen atmosphere. Its synthesis mechanism and dehydriding behavior were systematically investigated by XRD, FTIR, TG/DSC and TPD analyses. These results show that the synthetic process of Ca(AlH 4)2 can be divided into two steps: the first step is ball-milling NaH/Al with CeAl4 under hydrogen atmosphere to form CeAl4-doped NaAlH4, the second step is ball-milling the as-synthesized CeAl4-doped NaAlH4 and CaCl2 to form CeAl4-doped Ca(AlH4)2. The CeAl 4-doped Ca(AlH4)2 can desorb more than 5.5 wt.% hydrogen below 200 °C with an acceptable reaction kinetics, and shows attractive dehydriding behavior better than that of Ca(AlH4) 2 directly prepared by primary NaAlH4 and CaCl 2.

Ca(AlH4)2 was synthesized by ball-milling the mixture of NaAlH4 and CaCl2 in a molar ratio of 2:1 and under a hydrogen atmosphere of 1 MPa. The results indicate that the reactants have entirely transformed to Ca(AlH4)2 with a byproduct of NaCl after ball-milling for 48 h. Investigations of dehydriding behavior of the as-prepared Ca(AlH4)2 sample show that approximately 5.2 wt.% of hydrogen is desorbed during the first two dehydrogenation reactions of Ca(AlH4)2, which exhibit an exothermic event at 148 °C and an endothermic event at 267 °C, respectively. The high temperature dehydrogenation at 267 °C mainly concentrates on the thermolysis of CaAlH5 intermediate. FeF3-doped Ca(AlH4) 2 system represents an improved dehydriding performance, the dehydrogenation temperature of CaAlH5 intermediate is decreased about 43 °C. After FeF3 doping, the apparent activation energy of CaAlH5 is reduced from 153.4 kJ/mol (undoped) to 88.3 kJ/mol (doped), it renders a possibility to realize the rehydrogenation of CaAlH5. The catalytic effect is attributed to a fluorine transfer reaction that occurred to generate CaF2 and Fe catalysts.

The methods for the preparation of quasicrystalline intermetallic compounds in the protective matrix in the systems Al65Cu22Fe 13 and Al54Cu9Mg37 were developed. They are formed both earlie

Efficient electrical wiring of electrode is becoming a key issue in the design of Li-ion batteries utilizing insulating compounds. Presently, approaches acting at the material level are being pursued by combining techniques in decreasing the size of the particles and the use of carbon nanopainting. Here, we report the texturation of the Al current collector as an additional means to improve electrode kinetics. Aluminum electrodeposits were grown on aluminum and stainless steel substrates from ionic liquid electrolytic baths using pulse currents. The Al deposits, having a hilly morphology, nicely adhere to the substrate. Electrodes using these electrodeposits with host LiFePO4 powders were shown to display excellent capacity retention and high rate capabilities.

Ti-Zr-codoped NaAlH4 exhibits improved hydrogen desorption and reabsorption properties compared with sole Ti- or Zr-doped alanate. This contribution aims on reversible hydrogen storage in such material under realistic operation conditions. Results on isothermal dehydrogenation-rehydrogenation cycles at 125 °C and desorption at 4 bar hydrogen back-pressure are presented, proving NaAlH4 to be a suitable hydrogen material in combination with proton exchange membrane fuel cells.

An improved reactive transport model of a metallorganic chemical vapor deposition process for the growth of aluminum films from dimethylethylamine alane is developed. The computational fluid dynamics model is built under PHOENICS software for the simulation of the coupled fluid flow, heat transfer, and chemistry. The growth mechanism of aluminum films is based on well-established, in the literature, reaction order and activation energy of gas-phase and surface reactions. The improvement of the model against a simplified model is established. The interplay of reaction and transport is elucidated. In particular, the important effects of the gas-phase reaction and of the showerhead system are revealed; accounting for gas-phase along with surface reactions for the flow details in the showerhead and for the three-dimensional geometry induced by the distribution of the holes in the showerhead yields substantial enhancement of the predictive capability of the model. The satisfactory agreement between model predictions and growth-rate measurements allows one to understand and improve the process. The model is further used to investigate the effect of key operating parameters on the characteristics of the aluminum films. Simulation results are suggestive of modifications in the operating parameters that could enhance the growth rate and its spatial uniformity.

Tuning the hydrogen storage properties of complex metal hydrides is of vast interest. Here, we investigate the hydrogen release and uptake pathways for a reactive hydride composite, LiBH4-NaAlH4 utilizing in situ synchrotron radiation powder X-ray diffraction experiments. Sodium alanate transforms to sodium borohydride via a metathesis reaction during ball milling or by heating at T～95 °C. NaBH4 decomposes at ～340 °C in dynamic vacuum, apparently directly to solid amorphous boron and hydrogen and sodium gas and the latter two elements are lost from the sample. Under other conditions, T=400 °C and p(H2)=～1 bar, NaBH4 only partly decomposes to B and NaH. On the other hand, formation of LiAl is facilitated by dynamic vacuum conditions, which gives access to the full hydrogen contents in the LiBH4-NaAlH4 system. Formation of AlB2 is observed (T～450 °C) and other phases, possibly AlBx or Al1-xLixB2, were observed for the more Li-rich samples. This may open new routes to the stabilization of boron in the solid state in the dehydrogenated state, which is a challenging and important issue for hydrogen storage systems based on borohydrides.

The thermal behavior of poly(methyl methacrylate) (PMMA) was studied in the presence of AlBr3 using TG-DTA-DTG, IR and Py-GC-MS techniques. Degradation products were identified. It was found that PMMA started degrading at a lower temperature du

In this paper, we report for the first time on the room-temperature preparation of metallic aluminum nanoparticles by the pulsed sonoelectrochemical method. The prepared nanoparticles were characterized by X-ray diffraction (XRD), high-resolution scanning

Electrochemical deposition of aluminum and lead from basic molten AlCl3-NaCl-KCl mixture on an aluminum electrode at 180 °C was studied by the methods of voltammetry, potential and current transient and constant current deposition. The depositi

Electrorefining of aluminum alloy was investigated using AlCl3 and 1-ethyl-3-methyl-imidazolium chloride (EMIC) (molar ratio AlCl3:EMIC = 1.65:1) ionic liquid electrolyte on copper and aluminum cathodes at temperature of 90 ± 3 °C an

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BaAlH5 and Ba2AlH7 were successfully synthesized through reactive ball milling commercially available BaH2 and Al powders for the first time. The effects of the mole ratios of BaH2/Al on the phase for