Abstract
Hydrozincite and spherocobaltite phases were obtained by coprecipitation of a mixture of zinc and cobalt nitrates using NaHCO3 at 60 degrees C and pH=8. The solid precursor obtained was calcined in air at 400-800 degrees C. The precursor and ZnCo2O4 were also exposed to gamma-ray doses of 0.4, 0.8 and 1.6 MGy. A nanostructuredd ZnCo2O4 spinel was obtained after calcination. X-ray diffraction analysis showed that the cubic ZnCo2O4 phase was thermally stable in the temperature range 400-800 degrees C. The grain size of the ZnCo2O4 phase was found to increase with increasing calcination temperature and gamma-ray dose. X-ray diffraction results and SEM confirmed that gamma-irradiation has a marked effect on grain growth. Total surface area S-BET of the solid precursor was found to increase with increasing gamma-ray dose owing to the creation of new pores. A marked decrease in S-BET was observed after calcining at 400-800 degrees C or after exposure to gamma-rays. The decrease in S-BET can be explained in terms of increasing crystallite size.