Synthesis and characterization of the NiAl2O4, CoAl2O4 and ZnAl2O4 spinels by the polymeric precursors method

The spinels constitute an important group of materials with great technological appeal, being able to be applied as pigments, refractory, catalysts and electronic ceramics. In this paper, we reported the preparation of nanocrystalline NiAl2O4, CoAl2O4 and ZnAl2O4 phases by Pechini method. This method employs the dissolution of cations precursors in a citric acid aqueous solution. Due to the high chemical homogeneity, cation segregation during thermal decomposition is minimal. The resulting powders were characterized by XRD, N-2 adsorption/desorption curves (BET curves) and SEM. The X-ray diffraction patterns show that the synthesis is efficient to produce single-phased NiAl2O4, CoAl2O4 and ZnAl2O4 powders and the crystallite sizes were 12,34 and 20 nm, respectively. The micrographs show the formation of soft agglomerates with irregular morphology constituted by the superposition of the quite fine particles. (C) 2008 Elsevier B.V. All rights reserved.