In situ observation of the formation of hollow zinc oxide shells

Single crystal zinc particles, 1 - 2 μ m in diameter, were observed in situ with transmission electron microscopy during sublimation. The rate of sublimation is strongly dependent on the presence of a surface oxide layer. Near 375 ° C , minimally oxidized Zn surfaces sublime in tens of seconds, consistent with a model in which the particle behaves similarly to an isolated microscale effusion cell. By contrast, zinc particles fully enclosed by oxide sublime less than one-tenth as quickly. These results provide new insight into the synthesis mechanisms of hollow ZnO microspheres and related structures formed from metallic zinc at elevated temperatures.