Untersuchungen �ber Aluminiumhydroxyde und -oxyde, 4. Mitt.: Beschreibung zweier neuer Aluminiumoxydformen, die bei hydrothermaler Zersetzung von metallischem Aluminium gefunden wurden

Torkar, K.; Krischner, H.

doi:10.1007/bf00899804

Cited by 11 publications

(3 citation statements)

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“…Hydrothermal oxidation of metals have been examined for the synthesis of oxides. Thus, Torker et al , examined the reaction of aluminum metal in water in the temperature range of 200−500 °C and found that various phases such as KI form (Tohdite) and α*-alumina were formed, depending on the reaction conditions. On the other hand, the use of alcohols in place of water for the hydrothermal oxidation of metals have never been examined from the viewpoint of inorganic synthesis although the reaction has been examined from the viewpoint of metal corrosion in alcohols .…”

Section: Discussionmentioning

confidence: 99%

Alkoxyalumoxanes

1999

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The reaction of aluminum alkoxide or aluminum metal in primary alcohols at 250-300 °C was examined, and the products were characterized by powder X-ray diffraction, IR spectroscopy, MAS NMR spectroscopy, thermal analyses, and scanning electron microscopy. The products had the layer structure of boehmite with alkyl pendant groups derived from the solvent alcohols, the alkyl moieties of the aluminum alkoxide being completely expelled from the product, and the basal spacing linearly increased with the carbon number of the alcohol. The alkyl groups were stable beyond the boiling point of the parent alcohol, suggesting that they are covalently bonded to the boehmite layers. All of the data suggest that the products are the alkyl derivatives of boehmite (alkoxyalumoxanes) having an empirical formula of AlO(OH) (1-x) (OR) x . The value x depended on the alcohol used as the solvent and varied from 0.62 to 0.21. Partial decomposition of alkyl moieties still preserved the overall structure of alkoxyalumoxane.

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Section: Discussionmentioning

confidence: 99%

Alkoxyalumoxanes

1999

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“…Yamaguchi et al (1964a) synthesized T using AlF 3 as a "mineralizer", but they were also successful in synthesizing "tohdite" in the presence of trace amounts of titanium sulfate. Phase T appears to correspond to phases synthesized by Torkar (1960) and by Aramaki & Roy (1963) from F-free compositions. Phase T occurs naturally in Australian bauxite deposits (Tilley & Eggleston 1994).…”

Section: Phase Tmentioning

confidence: 90%

STABILITY RELATIONS OF ALUMINUM HYDROXY-FLUORIDE HYDRATE, A RALSTONITE-LIKE MINERAL, IN THE SYSTEM AlF3-Al2O3-H2O-HF

Rosenberg

2006

The Canadian Mineralogist

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“…Numerous research works [1][2][3][4][5][6][7][8][9], have demonstrated this, though the conclusions are sometimes discrepant. The transformations of the structure of aluminium hydroxides during heating up to the formation of new crystalline products depend on many factors, such as the type and origin of the aluminium hydroxide, grain size, chemical purity, heating rate, calcination time, atmosphere, mineralizator additives and others.…”

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confidence: 86%

The dehydroxylation of aluminium hydroxides and the kinetics ofα-Al2O3 formation

Pyzalski¹,

Wójcik²

1990

Journal of Thermal Analysis

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Studies were made of the dehydroxylation of several aluminium hydroxide modifications and the kinetics of a-A1203 formation. The investigated samples differed in both mineral composition and the level of alkali admixtures. It was found that the rate of formation and the quantity of a-A1203 depend mainly on the purity of the aluminium hydroxides, while the transition forms of alumina depend on the initial type of the aluminium hydroxide.Alumina is currently a valuable construction material in the various branches of industry. Its wide-ranging applications demand that alumina fulfils very high requirements as concerns chemical purity, hardness, crystallographic structure, degree of comminution and many other physieochemical features.Alumina is chiefly obtained by the dehydroxylation of aluminium hydroxides. The final aim is most often the manufacture of the most stable form of A1203 i.e. a-A1203, corundum. Corundum has exellent properties, such as high hardness, thermal resistance and high melting temperature. The final physicochemical properties of the produced ceramic material and the economy of the technological process of its manufacture depend on the rate of formation and the quantity of a-A1203.The dehydroxylation of aluminium hydroxides is a very complicated process. Numerous research works [1][2][3][4][5][6][7][8][9], have demonstrated this, though the conclusions are sometimes discrepant. The transformations of the structure of aluminium hydroxides during heating up to the formation of new crystalline products depend on many factors, such as the type and origin of the aluminium hydroxide, grain size, chemical purity, heating rate, calcination time, atmosphere, mineralizator additives and others. Irrespective of these factors, greater or smaller amounts of a-A1203 are always obtained if the calcination temperature is adequately high. The proposed schemes of dehydroxylation differ because of the various methods of manufacturing of John Wiley & Sons, Limited, Chichester Akaddmiai Kiad6, Budapest

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Untersuchungen �ber Aluminiumhydroxyde und -oxyde, 4. Mitt.: Beschreibung zweier neuer Aluminiumoxydformen, die bei hydrothermaler Zersetzung von metallischem Aluminium gefunden wurden

Cited by 11 publications

References 0 publications

Alkoxyalumoxanes

Alkoxyalumoxanes

STABILITY RELATIONS OF ALUMINUM HYDROXY-FLUORIDE HYDRATE, A RALSTONITE-LIKE MINERAL, IN THE SYSTEM AlF3-Al2O3-H2O-HF

The dehydroxylation of aluminium hydroxides and the kinetics ofα-Al2O3 formation

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