Bending of MgO tubes: Mechanically induced hexagonal phase of magnesium oxide

The present work constitutes a study of the response of magnesium oxide nanotubes on the bend deformation. Our molecular-dynamics simulations show that the structure of the MgO tubes being face centered cubic at ambient conditions is transformed under mechanically induced buckling stress to hexagonal near the tube bend. This transformation occurs through a break of the Mg-O bonds between two adjacent Mg₂O₂ tetragons and the formation of Mg₃O₃ hexagons. Ab initio density-functional band-structure calculations were performed to predict the structural and electronic properties of hexagonal MgO phase and to compare with those for the cubic $B1$ and $B2$ MgO phases.