Nanoindentation pop-in in oxides at room temperature: Dislocation activation or crack formation?

Xufei Fang*, Hanna Bishara, Kuan Ding, Hanna Tsybenko, Lukas Porz, Marion Höfling, Enrico Bruder, Yingwei Li, Gerhard Dehm, Karsten Durst

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Most oxide ceramics are known to be brittle macroscopically at room temperature with little or no dislocation-based plasticity prior to crack propagation. Here, we demonstrate the size-dependent brittle to ductile transition in SrTiO3 at room temperature using nanoindentation pop-in events visible as a sudden increase in displacement at nominally constant load. We identify that the indentation pop-in event in SrTiO3 at room temperature, below a critical indenter tip radius, is dominated by dislocation-mediated plasticity. When the tip radius increases to a critical size, concurrent dislocation activation and crack formation, with the latter being the dominating process, occur during the pop-in event. Beyond the experimental examination and theoretical justification presented on SrTiO3 as a model system, further validation on α-Al2O3, BaTiO3, and TiO2 are briefly presented and discussed. A new indentation size effect, mainly for brittle ceramics, is suggested by the competition between the dislocation-based plasticity and crack formation at small scale. Our finding complements the deformation mechanism in the nano-/microscale deformation regime involving plasticity and cracking in ceramics at room temperature to pave the road for dislocation-based mechanics and functionalities study in these materials.

Original languageEnglish
Pages (from-to)4728-4741
Number of pages14
JournalJournal of the American Ceramic Society
Issue number9
StatePublished - Sep 2021
Externally publishedYes


  • crack formation
  • dislocation
  • nanoindentation pop-in
  • oxide
  • size effect


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