Direct observation of Li diffusion in Li-doped ZnO nanowires

Guohua Li, Lei Yu, Bethany M Hudak, Yao-Jen Chang, Hyeonjun Baek, Abhishek Sundararajan, Douglas R Strachan, Gyu- Chul Yi and Beth S Gution, 2016

Image courtesy of Mater. Res. Express

Abstract

The direct observation of Li diffusion in Li-doped zinc oxide nanowires (NWs) was realized by using in situ heating in the scanning transmission electron microscope (STEM). A continuous increase of low atomic mass regions within a single NW was observed between 200 °C and 600 °C when heated in vacuum, which was explained by the conversion of interstitial to substitutional Li in the ZnO NW host lattice. A kick-out mechanism is introduced to explain the migration and conversion of the interstitial Li (Lii) to Zn-site substitutional Li (LiZn), and this mechanism is verified with low-temperature (11 K) photoluminescence measurements on as-grown and annealed Li-doped zinc oxide NWs, as well as the observation of an increase of NW surface roughing with applied bias.

Impact Statement

Li-doped ZnO nanowires were used to study Li diffusion upon in situ heating, where a continuous increase of low atomic mass regions within a single NW was observed between 200 °C and 600 °C. Using EELS and photoluminescence measurements a kick-out mechanism was introduced to explain the migration and conversion of the interstitial Li (Lii) to Zn-site substitutional Li (LiZn).