Role of dislocation climb on twin boundary and antiphase boundary formations in inverse-spinel MnAl2O4

The defects, e.g., stacking faults (SFs), antiphase boundaries (APBs), and twin, have been considered the critical components commonly introduced during the synthesis process of spinel oxides. In this study, employing advanced transmission electron microscopy, the formation mechanisms of twin and APBs in MnAl2O4 spinel oxide were clarified. Atomic resolution scanning transmission electron microscopy image and image simulation clarify that MnAl2O4 holds the inverse-spinel-typed structure. Detailed analysis of the twin structure reveals that the asymmetric twin structure in MnAl2O4 forms through an (Mn, Al)-containing plane missing by dislocation climb-up and then continuous shearing on {111} plane. APB forms by dis-location climb-down on an (Mn, Al)-containing {111} plane. The detailed lattice distortion induced by dislocation climb-down was analyzed by geometric phase analysis. The burgers vector for APB formation is identified as a/6[111]+a/4[110]. Frank dislocation of a/6[111] climb-down and the lattice strain from in-troducing the extra plane brings a displacement of a/4 [110], which results in terrace-ledge-like morphology of APBs. This study provides a detailed understanding of twin and APB formation mechanisms in inverse-spinel-typed MnAl2O4.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

This study clarifies the formation mechanisms of twin and antiphase boundaries (APBs) in MnAl2O4 spinel oxide using advanced transmission electron microscopy. It is found that MnAl2O4 has an inverse-spinel structure. The asymmetric twin structure is formed through dislocation climb-up and continuous shearing on the {111} plane, while APBs form through dislocation climb-down on a (Mn, Al)-containing {111} plane. The detailed lattice distortion induced by dislocation climb-down and the formation of APBs is analyzed. This study provides a detailed understanding of twin and APB formation mechanisms in inverse-spinel MnAl2O4.