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Nanostructured Oxides in Chemistry: Characterization and Properties

“…466 The number and nature of the intermediates as well as the temperature(s) of the γ-to-θ transformation depends on a wide number of parameters as the nature of the precursors or preparation pH 467 and, certainly, the initial size of the gamma phase. 468 The R phase is obtained by a nucleation growth mechanism by which the key step is the anion packing reordering from the cubic to a hexagonal structure. 20,464,465 The analysis of the θ f R phase transformation mechanism, whether it is a shear mechanism with the shear in an oxygen lattice direction or a diffusional one as a part of the typical "nucleation and growth" model mechanism, has the subject of many studies and recently reviewed.…”

Production of γ-Al<sub>2</sub>O<sub>3</sub> from Kaolin

“…Until now, a large variety of methods such as sol-gel synthesis from calcination of boehmite [9], poly hydroxo aluminum-poly vinyl alcohol [10], laser ablation of an aluminum target in an oxygen atmosphere [13], hydrolysis of alumina alkoxide [14], thermal decomposition of aluminum sulfate [15], metal organic chemical vapor deposition with Al(CH 3 ) 3 [16] have been used to prepare γ-alumina.…”

Synthesis and Characterisation of γ-Al2O3 with Porous Structure and Nanorod Morphology

“…Until now, a large variety of methods such as the thermal decomposition of aluminium sulfate 17 sol-gel synthesis, 18 plasma spray decomposition of oxides, 19 arc-discharge methods, 20 precipitation, 21 polyhydroxoaluminumpolyvinylalcohol, 22 laser ablation of an aluminium target in an oxygen atmosphere, 23 non-ionic surfactant, 24 metal organic chemical vapour deposition with Al(CH 3 ) 3 , 25 electron beam evaporation and spray pyrolysis method, 26 hydrolysis of alumina alkoxide, 27 have been employed to prepare γ-Al 2 O 3 . Furthermore, the γ-Al 2 O 3 was prepared by dehydration of γ-AlOOH in the temperature range of 450-750 °C, 28 and the morphology of γ-AlOOH stays the same.…”