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In situ study of the recovery of nanoindentation deformation of the (100) face of MgO crystals by atomic force microscopy

Surface Science
Publication Date
DOI: 10.1016/s0039-6028(99)00909-7
  • Atomic Force Microscopy
  • Low-Index Single Crystal Surfaces
  • Magnesium Oxide
  • Single Crystal Surfaces
  • Surface Diffusion
  • Surface Relaxation And Reconstruction
  • Surface Stress
  • Surface Structure
  • Morphology
  • Roughness
  • And Topography


Abstract Results are described and discussed of an in situ atomic force microscopy study on the evolution of the surface morphology around indentations made on the (100) cleavage face of MgO crystals by square pyramidal silicon tips for loads up to 10 μN. It was found that: (1) nanoindentation does not introduce plastic deformation on the surface; (2) an indented surface always tends to heal with time but the time t of healing increases with penetration depth d (i.e., with applied load); (3) for indentations with d<ca. 17 nm the penetration depth decreases with increasing time following a power-law dependence; (4) with decreasing d, the indentation diameter a first increases and then decreases, exhibiting a peak at a depth of about three to four monolayers; (5) the hill height increases approximately linearly with penetration depth; and (6) indentation leads to the movement of cleavage steps with rates of up to 1.3×10 −11 m s −1. Analysis of the kinetics suggests that the recovery of indented surfaces of MgO crystals occurs by local reorganization, and volume and surface diffusion processes. A model of the formation of an indentation impression, involving the penetration of the indenter under applied load first into the initial surface layer and subsequently deep into the bulk of the crystal, is proposed and used to explain the recovery of nanoindentation deformation.

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