Synthesis and characterization of nanocrystalline CoAl2O4 spinel powder by low temperature combustion

Single-phase nanocrystalline CoAl2O4 spinel powder with a high surface area has been directly prepared by an auto-ignited gel combustion process using citric acid as a reductant/fuel and metal nitrates as oxidants. The molar ratio of fuel to nitrates in the redox mixture and the subsequent calcination upon the burnt powder were found to have a significant influence on the characteristics of the as-synthesized CoAl2O4 crystallites. By controlling the CA/NO3− ratio and calcination temperature, homogeneous crystalline CoAl2O4 powders with different particle sizes from 9 to 110 nm have been obtained. Gel formation, combustion behavior, microstructures and properties of the powders were characterized using DTA/TGA, FT-IR, XRD, FESEM, TEM, BET and UV/vis/IR.