Synthesis and Electrosurface Properties of One- and Two-Component Nanostructures

One- and two-component (titanium and aluminum oxides) oxide nanostructures are synthesized by molecular layer-by-layer deposition from the gas phase onto silicon oxide and boehmite substrates. Two-component nanostructures are prepared by the consecutive deposition of nanolayers of aluminum and titanium oxides onto a dispersed silica substrate. Electrosurface properties of thus-prepared samples are studied and compared. It is shown that the positions of the isoelectric point and the point of zero charge of a 5TiO₂/5Al₂O₃/SiO₂ composite sample are governed by an outer titanium oxide nanolayer and are similar to those of bulk titanium oxide and a nanostructured film of titanium oxide deposited onto an aluminum hydroxide substrate.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 4, 2005, pp. 469–474.Original Russian Text Copyright © 2005 by Bogdanova, Ermakova, Chikhachev, Sidorova, Aleksandrov, Savina.     

Colloidal properties of aqueous dispersions of ultradispersed Al<Subscript>2</Subscript>O<Subscript>3</Subscript> prepared by explosion synthesis

The electrosurface properties of aluminum oxide particles prepared by shock—wave loading of aluminum powder in an oxygen-containing atmosphere and the aggregation stability of its aqueous dispersions are studied by the macroelectrophoresis method, potentiometric titration, and photometry. The enhanced stability of the dispersions in acid media and in the vicinity of the isoelectric point compared to that in alkaline media is explained by the effect of the structural component of the disjoining pressure, which appears due to the predominant hydration of the cationic forms of aluminum that are present on the surface of dispersed phase particles.Translated from Kolloidnyi Zhurnal, Vol. 67, No. 1, 2005, pp. 128–131. Original Russian Text Copyright © 2005 by Chiganova, Nafikova.     

Finely Dispersed Aluminum Oxide as a Catalyst for Purification of Fume Gases to Remove Polycyclic Aromatic Hydrocarbons

The possibility of using finely dispersed aluminum oxide for catalytic purification of effluent gases to remove noxious substances formed in calcination of coal blank parts in fabrication of graphite electrodes was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 761–766.Original Russian Text Copyright © 2005 by Afanas’ev, Permyakov, Avvakumov.     

The Adsorption and Curing Behaviors of the Epoxy/Amidoamine System in the Presence of Metal Oxides

The curing and adsorption behaviors of an epoxy/amidoamine system under the influence of iron, aluminum, and zinc oxides are studied by using differential scanning calorimetry (DSC) and diffuse reflectance infrared spectroscopy (DRIFT). From DRIFT, it is obtained that the amidoamine curing agent is preferentially adsorbed on the three metal oxide surfaces. The amount of amidoamine adsorbed is in the order of iron oxide>zinc oxide>aluminum oxide. Moreover, the iron and zinc oxides adsorb resins more firmly than the aluminum oxide. The results of DSC analyses indicate that more amine related exotherms are found in the specimen filled with the iron oxide but more amide related exotherms are found in the zinc oxide added specimens and they are related to the difference in the preferential adsorption found on three metal oxides. The curing characteristics are also changed in the presence of metallic fillers and the greatest change is obtained from the specimen containing the iron oxide.This revised version was published online in November 2005 with corrections to the Cover Date.     

Formation and dielectric properties of anodic oxide films on Zr–Al alloys

Zr–Al alloys containing up to 26 at.% aluminum, prepared by magnetron sputtering, have been anodized in 0.1 mol dm⁻³ ammonium pentaborate electrolyte, and the structure and dielectric properties of the resultant anodic oxide films have been examined by grazing incidence X-ray diffraction, transmission electron microscopy, Rutherford backscattering spectroscopy, and AC impedance spectroscopy. The anodic oxide film formed on zirconium consists of monoclinic and tetragonal ZrO₂ with the former being a major phase. Two-layered anodic oxide films, comprising an outer thin amorphous layer and an inner main layer of crystalline tetragonal ZrO₂ phase, are formed on the Zr–Al alloys containing 5 to 16 at.% aluminum. Further increase in the aluminum content to 26 at.% results in the formation of amorphous oxide layer throughout the thickness. The anodic oxide films become thin with increasing aluminum content, while the relative permittivity of anodic oxide shows a maximum at the aluminum content of 11 at.%. Due to major contribution of permittivity enhancement, the maximum capacitance of the anodic oxide films is obtained on the Zr–11 at.% Al alloy, being 1.7 times than on zirconium at the formation voltage of 100 V.     

Photosorption of oxygen and nitric oxide by aluminum and silicon oxides under conditions of troposphere

The photosorption characteristics of finely divided -Al₂O₃ and SiO₂ with the state of the surface formed under long-term action of atmospheric air, were studied. The effective quantum yields and the action spectra of photoinduced adsorption of oxygen and nitric oxide were determined. It has been assumed that the absence of noticeable photoinduced adsorption of halogenated compounds on these powdered aluminum and silicon oxides is due to their low degree of crystallinity.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 3, 2005, pp. 190–194.Original Russian Text Copyright © 2005 by Zakharenko, Moseichuk, Parmon.     

Effect of silica on the stability of the nanostructure and texture of fine-particle alumina

The effect of the modification of aluminum oxide with silicon oxide on the stability of fine-particle Γ- and δ-Al₂O₃ phases upon heat treatment in the wide temperature range of 550–1500°C was studied. It was found that the Γ- and δ-Al₂O₃ phases modified with silica are thermally stable up to higher temperatures than pure aluminum oxide. This is due to changes in the real structure of the modified samples, specifically, an increase in the concentration of extensive defects stabilized by hydroxyl groups bound to not only aluminum atoms but also silicon atoms. It is likely that Si-OH groups, which are thermally more stable than Al-OH groups, stabilize the microstructure of Γ- and δ-Al₂O₃ to higher temperatures, as compared with aluminum oxide containing no additives. Simultaneously, an increase in the thermal stability of the modified samples is accompanied by the retention of a high specific surface area and a developed pore structure at higher treatment temperatures.     

Large-scale preparation of aluminum borate-coated aluminum oxide nanowires

Single-crystal and uniform aluminum borate (Al₄B₂O₉)-coated aluminum oxide nanowires have been synthesized in high purity and in large yield via a reaction of metal aluminum with boron oxide in the presence of carbon nanotubes (CNTs). The aluminum oxide nanowires exhibit a well-crystallized one-dimensional structure with diameters ranging from 50 to 70 nm, and the Al₄B₂O₉ have a coating thickness of about 1-5 nm. CNTs play a crucial role in the formation of the important ceramic nanowires, by providing a platform to grow the composite structure. The growth mechanism was proposed by the detailed microscopy observations.     

Study of the catalysts for fuel combustion reactions: XX. Thermal stability and other properties of the CeO2-MgO-Al2O3 system

The effect of simultaneous addition of magnesium and cerium cations on the structure formation and properties of aluminum oxide obtained from hydroxides with different phase compositions by thermal treatment at 773–1573 K is studied. At temperatures lower than 1273 K, the effect of specific surface area stabilization is observed for the samples. It is found that spherical aluminum oxide modified with Mg and Ce cations exhibits high mechanical strength upon calcination atT > 1373 K. Modified samples calcined at 1573 K are catalytically active in the CH₄ oxidation reaction     

Crystal structure of Eu-doped magnetoplumbite-type lanthanum aluminum oxynitride with emission site splitting

Eu-doped lanthanum aluminum oxynitride (LaAl₁₂(O,N)₁₉) with magnetoplumbite structure was prepared by nitridation of the oxide precursor obtained from aluminum glycine gel and subsequent post-annealing. Eu-doped lanthanum aluminum oxynitride exhibited blue light emission at 440 nm with a shoulder at 464 nm under excitation at 254 nm. Isostructural Eu-doped calcium aluminum oxide (CaAl₁₂O₁₉) exhibited a single emission peak at 415 nm. Structural refinement using neutron powder diffraction indicated that the lanthanum site occupied partially by Eu²⁺ splits into 2d and 6h sites in the aluminum oxynitride. The longer emission and the shoulder peak in the former aluminum oxynitride were observed in relation to the increasing covalency as well as crystal field splitting around doped Eu²⁺ induced by site splitting involved with the two kinds of anions.     

Sorbent based on aluminum oxide modified with Tiron

The adsorption of Tiron (disodium 4,5-dihydroxy-m-benzenedisulfonate) on aluminum oxide surface was studied, and optimum conditions for the modification of aluminum oxide surface were determined. The sorption of copper(II) on aluminum oxide modified with Tiron was studied. It was shown that the sorption of copper occurs by the mechanism of complex formation with the modifier (Tiron). The composition of the surface complex and its stability constant were determined: Cu: Tiron = 1: 1, logβ = 14.0 ± 0.4. Original Russian Text ? T.I. Tikhomirova, S.S. Kubyshev, A.V. Ivanov, P.N. Nesterenko, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 7 pp. 1360–1364.     

Effect of ac Polarization on Characteristics of Coatings formed from Polyphosphate Electrolytes of Ni(II) and Zn(II)

Characteristics of microplasma-produced coatings formed on an aluminum alloy under anodic and combined anodic-cathodic polarizations in electrolytes with polyphosphate complexes of Ni(II) and Zn(II) are compared.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005, pp. 253–259.Original Russian Text Copyright © 2005 by Boguta, Rudnev, Terleeva, Belevantsev, Slonova.     

Pseudo-Topochemical Synthesis of α-Fe in Aqueous Solution Using an Aluminum Matrix

Processes occurring in synthesis of α-Fe from a Fe(III) solution using an aluminum matrix were studied. The reaction kinetics strongly depends on the state of the matrix.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 2, 2005, pp. 177–183.Original Russian Text Copyright © 2005 by Dresvyannikov, Kolpakov.     

The use of alumatrane for the preparation of high‐surface‐area nickel aluminate and its activity for CO oxidation

Supported nickel has been used in a wide range of applications for industrial reactions, such as steam reforming, hydrogenation and methanation. In this work, nickel aluminate was prepared by the sol–gel process using alumatrane as the alkoxide precursor, directly synthesized from the reaction of inexpensive and available compounds, aluminum hydroxide and TIS (triisopropanolamine) via the oxide one pot synthesis (OOPS) process. Various conditions of the sol–gel process, such as pH, calcination temperature, hydrolysis ratio and ratio of nickel to aluminum, were studied. All samples were characterized using FTIR, TGA, XRD, TPR, DR‐UV and BET. The BET surface area was in the range of 340–450 m²/g at the calcination temperature of 500 °C with a mesoporous pore size distribution. Catalyst activity testing in CO oxidation reaction depended on Ni:Al ratio and calcination temperature. Higher activity was obtained from higher Ni content and lower calcination temperature. In addition, catalysts prepared using alumatrane precursor had higher percentage conversion than those prepared using aluminum hydroxide precursor. Copyright © 2005 John Wiley & Sons, Ltd.     

Heterogeneous-catalytic fischer reaction

The catalytic synthesis of 7-azaindole and its 2-methyl derivative has been accomplished for the first time by cyclization of acetaldehyde and acetone 2-pyridylhydrazones in the presence of -Al₂O₃ and fluorinated aluminum oxide. The temperature dependence of the yields of reaction products — azaindoles and 2-aminopyridine — was studied. The cyclization of acetaldehyde 2-pyridylhydrazone proceeds under more severe conditions. The maximum yield of 7-azaindole is 15% at 450° on fluorinated aluminum oxide. The yield of 2-methyl-7-azaindole reaches 50% at 315°. Fluorinated aluminum oxide displays higher catalytic activity.See [1] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 656–658, May, 1972.     

Reaction of Germanium Tetrachloride with Chloro(phenyl)silanes in the Presence of Aluminum Chloride

The effect of the quantity of aluminum chloride on the direction and depth of reaction of germanium tetrachloride with chloro(phenyl)silanes of the general formula Ph_nSiCl_4−n (n = 1 – 3) was studied to show that radical exchange between germanium and silicon is initiated only if the mixture contains no less than 2.5–5 wt % of aluminum chloride. With trichloro(phenyl)silane, the radical exchange is initiated at 5 wt % of aluminum chloride and results in exclusive formation of trichloro(phenyl)germane. The reactions of GeCl₄ with dichlorodiphenylsilane and chlorotriphenylsilane in the presence of 2.5–7.5 wt % of aluminum chloride give dichlorodiphenylgermane as the major product, and at AlCl₃ concentrations of above 10 wt % the major product becomes to be trichloro(phenyl)germane.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 920–922.Original Russian Text Copyright © 2005 by Zhun’, Sbitneva, Chernyshev.     

Pillared Tagan Montmorrilonite in Cracking of Isopropylbenzene

Tagan montmorillonite clay fixed with aluminum and zirconium oxides was prepared, and its catalytic (in cracking of isopropylbenzene), adsorption, and structural characteristics were studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005, pp. 279–283.Original Russian Text Copyright © 2005 by Zakarina, Volkova, Shchukina, Khan.     

自组装铝/氧化铜和铝/氧化铁及其性能评估

本文分别采用模板法制备氧化铜纳米花, 水热法制备氧化铁纳米环, 并自组装制备了铝-氧化铜和铝-氧化铁2种铝热剂。自组装增大了异相材料之间的接触, 分别使得铝-氧化铜的反应放热量和压力由523 J·g^-1、1 858 kPa增加至1 069 J·g^-1、 4 389 kPa;铝-氧化铁的反应放热量和压力由1 448 J·g^-1、749 kPa增加至2 039 J·g^-1、2 280 kPa。两种铝热剂的放热量和压力差别较大, 且铝-氧化铜的静电感度高于大多数含能材料, 铝-氧化铁的撞击感度特别低, 显示出不同的应用特点。     

Determination of aluminum oxide in and on high-purity aluminum by a phenol dissolution method

A simple rapid determination of aluminum oxide in aluminum is described. Aluminum reacts with phenol at 180°C forming aluminum phenoxide but aluminum oxide does not. After the reaction, the aluminum oxide is filtered off and brought into aqueous solution by fusion with potassium hydrogensulfate for determination by atomic absorption spectrometry or by the 8-quinolinol spectrophotometric method. The reaction between aluminum and phenol is stoichiometric. The procedure is applicable to the determination of aluminum oxide in commercial aluminum metals of various forms. The method is relatively rapid and appears to be superior to the conventional bromine—methanol method.     

Study of chemical processes in the modification of epoxide polymers by aluminum oxide

The processes occurring during the modification of epoxy polymers by various polymorphic aluminum oxide modifications (γ-AlO(OH), γ-Al₂O₃, α-Al₂O₃) with epoxy groups were studied by the methods of IR Fourier spectroscopy, chemical analysis, and differential scanning calorimetry (DSC) by an example of a model compound (phenyl glycidyl ether). Two types of interactions were revealed: a direct chemical reaction of phenyl glycidyl ether with the surface hydroxy groups of alyminum oxide, and phenyl glycidyl ether homopolymerization. By processing by graphical method the data of chemical analysis on the diminishing in amount of epoxy groups in the course of the polycondensation reaction the value of activation energy 106–110 kJ mol⁻¹ of the process of phenyl glycidyl ether interaction with aluminum γ-oxide was determined.