Transparent glass-ceramics based on ZnO and ZnO:Co2+ nanocrystals

Glasses of the potassium zinc aluminum silicate system, undoped and doped with cobalt oxide, have been synthesized. Differential-thermal analysis and x-ray phase-diffraction analysis were used to study the crystallization physics and the nature of the phases precipitated when the starting glasses were heat treated in the temperature interval 680 degrees C-950 degrees C, as well as the effect of adding cobalt oxide on the phase-transformation processes. Transparent glass-ceramic materials based on only nanocrystals of zinc oxide were obtained, along with zinc oxide and beta-willemite. It is found that, when the cobalt-bearing glasses are heat-treated, cobalt ions from the starting glass initially enter into the resulting zinc oxide nanocrystals and, as the temperature is increased, into the beta-willemite nanocrystals. (C) 2015 Optical Society of America.