Emission of neutral Mg from single crystal MgO during abrasion with diamond

We report observations of atomic, neutral Mg emitted from single crystal MgO during abrasion with a diamond stylus. These emissions take the form of bursts, where the onset of each burst coincides with a slip event often associated with the passage of the stylus over a cleavage step. After the onset, the emission intensity grows gradually to a peak, then drops sharply. Similar bursts of neutral Mg are observed when indented single crystal MgO is heated to temperatures above 1300 °C. We attribute these bursts to the emission of neutral Mg during the relaxation of dislocation-related structures produced by mechanical deformation. Strain energy released as these structures annihilate at the surface drive Mg emission and heat the surrounding material. This heating accelerates subsequent relaxation, increasing the emission intensity until relaxation is complete and the emission rate drops sharply. © 2003 American Institute of Physics. @DOI: 10.1063/1.1532937#