Arrangement of polyhedral units for [0001]-symmetrical tilt grain boundaries in zinc oxide

Polycrystalline ZnO is used in a wide variety of electrical applications, and its properties are largely influenced by crystalline defects, such as grain boundaries (GBs). Therefore, in this study, the atomic structures of [0001]-symmetrical tilt GBs in ZnO have been characterized by scanning transmission electron microscopy, and the misorientation dependence of the atomic structures around GBs is thoroughly discussed based on the polyhedral-unit model. In addition to theoretical calculations, the polyhedral-unit arrangements for arbitrary tilt angles are described and predicted by a number-theory-based approach. The predicted structural-unit arrangements agreed well with those experimentally observed, indicating that geometrical restrictions determine the ZnO GB structures. Owing to the crystallographic relationship between the structural-unit Burgers vector and the GB-plane normal, the structural-unit arrangement was transformed at approximately 30 degrees, which is associated with a rigid-body translation from one grain to another. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study characterized the atomic structures of grain boundaries in ZnO using scanning transmission electron microscopy and discussed the misorientation dependence of the atomic structures around grain boundaries. The polyhedral-unit arrangements for arbitrary tilt angles were described and predicted by a number-theory-based approach, revealing that geometrical restrictions determine the ZnO grain boundary structures.