Solution combustion synthesis of MgAl2O4 using fuel mixtures

The paper reveals a new perspective concerning the rational fuel selection and the logical elaboration of the recipes for the MgAl2O4 solution combustion synthesis. It was shown that Mg(NO3)(2)center dot 6H(2)O and Al(NO3)(3)center dot 9H(2)O exhibit different behavior with respect to urea, glycine and beta-alanine. Urea proved to be the most adequate fuel for Al(NO3)(3)center dot 9H(2)O, while beta-alanine proved to be the most appropriate fuel for Mg(NO3)(2)center dot 6H(2)O. Considering that there is a predilection of metal nitrates with respect to these fuels, in the case of MgAl2O4 combustion synthesis best results were achieved when fuel mixtures (urea and P-alanine, urea and galycine) were used. The use of fuel mixtures allowed the formation of pure, nanocrystalline MgAl2O4 directly from the combustion reaction, without any subsequent annealing step. The use of a single fuel (urea, glycine or beta-alanine) led to the formation of an amorphous powder, which required further annealing in order to achieve the formation of crystalline MgAl2O4. (C) 2008 Elsevier Ltd. All rights reserved.