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Title: In situ transmission electron microscopy observation of ZnO polar and non-polar surfaces structure evolution under electron beam irradiation

In this paper, using in situ transmission electron microscopy, we investigated the dynamic reconstruction and evolution of ZnO polar and non-polar surfaces under high-energy electron beam irradiation. Electron beam radiolysis creates oxygen vacancies and a Zn rich (0001) surface. Positive polar charges at the (0001) surface expel loosely bonded Zn ions to diffuse away from the (0001) polar surface. As a result, mass loss was observed around the (0001) surface. Dehydration by the electron beam breaks the charge balance on the ( 000 1 ¯ ) polar surface. The negative charges on the ( 000 1 ¯ ) surface suppress the radiolysis effect and further absorb Zn ions to the surface to neutral the polar charges. The ideal stacking sequences of Zn ions in hexagonal ZnO structure can be considered as ABAB… along its c axis, while the absorbed individual Zn ion on the ( 000 1 ¯ ) surface occupies the C site to form three bonds with surface O ions beneath, instead of one bond in the ideal structure. With more Zn ion absorption and surface oxidization, new nanocrystals grow up from the ( 000 1 ¯ ) polar surface. Finally, new nanocrystals nucleated at the ( 01 1 ¯ 0 ) non-polar surface are driven by the electric field of the polar charges as well, for the Zn ions were always observed to absorb on the negatively charged [ 000 1 ¯ ] end of the newly formed ( 01 1 ¯ 0 ) surface layer.
Authors:
ORCiD logo [1] ;  [1] ;  [1]
  1. Georgia Inst. of Technology, Atlanta, GA (United States). School of Materials Science and Engineering
Publication Date:
Grant/Contract Number:
FG02-07ER46394; DMR-1505319
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 119; Journal Issue: 1; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Georgia Inst. of Technology, Atlanta, GA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; crystallography; nanowires; chemical elements; nanocrystals; surface structure; transmission electron microscopy; metal oxides; crystallographic defects; electron beam irradiation; transition metals
OSTI Identifier:
1469163
Alternate Identifier(s):
OSTI ID: 1234148

Ding, Yong, Pradel, Ken C., and Wang, Zhong Lin. In situ transmission electron microscopy observation of ZnO polar and non-polar surfaces structure evolution under electron beam irradiation. United States: N. p., Web. doi:10.1063/1.4939618.
Ding, Yong, Pradel, Ken C., & Wang, Zhong Lin. In situ transmission electron microscopy observation of ZnO polar and non-polar surfaces structure evolution under electron beam irradiation. United States. doi:10.1063/1.4939618.
Ding, Yong, Pradel, Ken C., and Wang, Zhong Lin. 2016. "In situ transmission electron microscopy observation of ZnO polar and non-polar surfaces structure evolution under electron beam irradiation". United States. doi:10.1063/1.4939618. https://www.osti.gov/servlets/purl/1469163.
@article{osti_1469163,
title = {In situ transmission electron microscopy observation of ZnO polar and non-polar surfaces structure evolution under electron beam irradiation},
author = {Ding, Yong and Pradel, Ken C. and Wang, Zhong Lin},
abstractNote = {In this paper, using in situ transmission electron microscopy, we investigated the dynamic reconstruction and evolution of ZnO polar and non-polar surfaces under high-energy electron beam irradiation. Electron beam radiolysis creates oxygen vacancies and a Zn rich (0001) surface. Positive polar charges at the (0001) surface expel loosely bonded Zn ions to diffuse away from the (0001) polar surface. As a result, mass loss was observed around the (0001) surface. Dehydration by the electron beam breaks the charge balance on the (0001¯) polar surface. The negative charges on the (0001¯) surface suppress the radiolysis effect and further absorb Zn ions to the surface to neutral the polar charges. The ideal stacking sequences of Zn ions in hexagonal ZnO structure can be considered as ABAB… along its c axis, while the absorbed individual Zn ion on the (0001¯) surface occupies the C site to form three bonds with surface O ions beneath, instead of one bond in the ideal structure. With more Zn ion absorption and surface oxidization, new nanocrystals grow up from the (0001¯) polar surface. Finally, new nanocrystals nucleated at the (011¯0) non-polar surface are driven by the electric field of the polar charges as well, for the Zn ions were always observed to absorb on the negatively charged [0001¯] end of the newly formed (011¯0) surface layer.},
doi = {10.1063/1.4939618},
journal = {Journal of Applied Physics},
number = 1,
volume = 119,
place = {United States},
year = {2016},
month = {1}
}