In situ reduction kinetics of NiCl2 in SiO2 gel matrix

Abstract

Silica gcls containing NiCl2 and dextrose have been reduced by heat-treating the gels under N2 atmosphere at 800 °C, 850 °C, 900 °C, and 950 °C, respectively. The influence of the volume ratio of ethyl alcohol to tetraethylorthosilicate and the amount of dextrose on the in situ reduction kinetics of NiCl2 in gel matrix have been investigated. The kinetic data on in situ reduction have been analyzed by a reduced time method which indicates that mixed mechanisms are operative. The predominant mechanism of reduction of NiCl2 in SiO2 gel matrix is of nucleation and growth type. The activation energies over different temperatures and fraction converted have been computed by the integration method.