Atomistic structure and segregation behavior in secondary structure and facet of Pr-doped ZnO ∑13 27.8° [0001] tilt grain boundary

Abstract

Much attention has been paid to grain boundaries (GBs) in ceramics owing to the impact on material properties. GB atomic scale investigations have so far mostly focused on the major structures. However, actual GB structure is more complex; there could be multiple types of atomistic structure and different morphology such as step and facet. As a case study to characterize these, we report extensive scanning transmission electron microscopy observations for a zinc oxide (ZnO) [0001] 27.8° (13, in the framework of coincidence site lattice theory) tilt GB doped with praseodymium (Pr) in this paper. In addition to the major structure that covers most of the (257̄0) GB plane area [Sato et al., Phys. Rev. B, 87, 140101 (2013)], two types of metastable atomistic structure are found. One is the secondary structure for the (257̄0) GB plane area, which is mostly found near facets. The other is a different type of atomistic structure formed in facets. Pr concentration is lower in the secondary structure than in the major structure. It is thus demonstrated that there is a variety in the atomistic structure and chemical composition within a single GB. © 2014 The Ceramic Society of Japan.