The effect of CuO on the grain growth of ZnO

The grain growth kinetics in the 1, 2, 3 and 4 wt.% CuO doped ZnO was studied using the simplified phenomenological grain growth kinetics equation Gn − Gn 0 = K0 · t · exp(−Q/RT ) together with microstructure properties of the sintered samples. The grain growth exponent value (n) was found to be 3 for 1, 2 and 3 wt.% CuO doped ZnO and 5.5 for 4 wt.% CuO doped ZnO. The apparent activation energy was decreased with CuO doping up to 3 wt.% from 250 kJ/mol to 150 kJ/mol but it was not changed significantly (155 kJ/mol) by 4 wt.% CuO doping. CuO doping up to 3 wt.% promoted the grain growth of ZnO whereas 4 wt.% CuO doping inhibited the grain growth of ZnO because of formation of Cu-rich secondary phase in the grain boundaries. C 2005 Springer Science + Business Media, Inc.