Chemical and structural properties of nickel hydroxide xerogels obtained by the sol-gel procedure in the presence of acetic acid

The sol-gel route to glasses and ceramics has attracted an increasing amoun t of scientific and technological interest recently. In this process, sols with different concentrations are used as precursors for xerogels and to pr oduce materials that consist of fine oxide particles. In the present work, nickel hydroxide gels have been obtained via the hydrolysis of a molecular precursor in the presence of acetic acid. The chemical aspects of the mater ial transformation have been studied by using Fourier transform infrared (F TIR) spectroscopy and differential scanning calorimetry (DSC) for different acetic acid contents and several heat-treatment temperatures. The carboxyl ic acid acts as a ligand at a molecular level in the precursor, therefore m odifying the entire hydrolysis and condensation process. Small-angle,X-ray scattering (SAXS) studies and density measurements have been performed for the structural characterization of the xerogels, A denser, final oxide mate rial is obtained when a higher acetic acid concentration is used, The poros ity of the dry gels coarsens when they are heat-treated up to a temperature of similar to 400 degrees C and its density decreases. The material that h as been heat-treated up to a temperature of 800 degrees C densifies and exh ibits a finer porosity. The chemical properties at a molecular level satisf actorily explain and are well correlated with the structural characteristic s of the studied material.