Structural stability and electronic structures of (1 1 1) twin boundaries in the rock-salt MnS

•   We observed the atomic structures of the (111) twin boundary in the rock-salt MnS.
•   Structural stability & electronic structure of (111) twin boundaries are studied.
• Discussions are further given to understand the properties of ionic compounds.

In the work, we report a theoretical and experimental study of the {1 1 1} twin boundaries in the rock-salt MnS using aberration-corrected transmission electron microscopy (TEM) and density functional theory. The experimental TEM images are supported by first-principle calculations. In comparison with magnesium oxide, we also explained why it is comparatively more stable for twins to exist in MnS rather than in MgO, which may help us better understand the properties of different ionic compounds.