Effect of NaOH on the Synthesis of Cobalt-Doped Willemite

Abstract

The interaction of ZnO with hydrosilica gel in the presence of a limited amount of NaOH and the doping of the resulting compounds with cobalt were studied. It was shown that only the molar ratio ν(NaOH)/ν(ZnO)/ν(CoCl₂) = 1/1.5/0.5 at 900°C leads to the formation of cobalt-doped α-Zn₂SiO₄. When the molar fraction of NaOH is less than unity, partial formation of cobalt-doped willemite occurs at 900°C simultaneously with doping of the unreacted ZnO. The most intense colors were observed at ν(NaOH)/ν(ZnO)/ν(CoCl₂) ratios of 0.6/1.7/0.3 and 0.8/1.6/0.4.