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摘要
The paper presents a new version of MgAl2O4 solution-combustion synthesis, based on the individual reactivity of Mg(NO3)(2) and Al(NO3)(3) with respect to various fuels. Beside the traditionally used fuels (urea, glycine, P-alanine), new organic reducing agents [monoethanolamine, triethanolamine, tris(hydroxymethyl)aminomethane and triethylenetetramine] have also been used. The study of the individual reactivities of Mc[(NO3)(2) and Al(NO3)(3) with respect to each of the previously mentioned fuels suggested that there is a predilection of the two metal nitrates for certain fuels: urea is the optimum fuel for Al(NO3)(3), whereas monoethanolamine represents the most suitable fuel for Mg(NO3)(2), It has been shown by X-ray diffraction and thermal analysis that the use of a single fuel in the MgAl2O4 low-temperature combustion synthesis leads to the formation of an amorphous powder. In this case, the formation of pure crystalline MgAl2O4 requires a subsequent thermal treatment at 900 degrees C with 1 h soaking time. On the other hand, the use of fuel mixtures containing urea and monoethanolamine or urea and beta-alanine proved to be the rational solution for the direct formation of MgAl2O4, It has been shown that, by using the above-mentioned fuel mixtures, one can obtain pure nanocrystalline MgAl2O4 straight from the combustion reaction, no additional calcination being necessary.
- 出版日期2008-2
