Plastic deformation of MgO under high-pressure cyclic compression
Phys. Rev. B 114, 144106 – Published 22 September, 2026
DOI: https://doi.org/10.1103/hb9r-jlsk
Abstract
The study of plastic deformation of magnesium oxide (MgO) is of great significance for both materials science and geoscience. In this work, we systematically investigate the plastic deformation of two grain sizes of MgO under cyclic compression using diamond anvil cell (DAC). The morphology, grain size, and aspect ratio of grain axis contrast of the postdeformed samples indicate that plasticity is accommodated primarily by grain fracture in coarse-grained MgO, whereas grain coalescence and grain growth resulting from grain rotation and realignment are observed in fine-grained MgO. Furthermore, an unexpected {111}〈11–2〉 slip, attributed to the dissociation of full 〈110〉 dislocations driven by high cyclic stress, is identified in MgO. These findings highlight the significance of high-pressure cyclic loading in activating unusual plastic deformation mechanisms of MgO, with implications for material design and understanding of seismic anisotropy in Earth's lower mantle.
