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Evaluating the effects of pillar shape and gallium ion beam damage on the mechanical properties of single crystal aluminum nanopillars


In situ TEM nanopillar compression experiments are widely used to study the mechanical behavior of nanoscale materials. Often, the pillars are fabricated using gallium-focused ion beam (FIB) milling from a bulk sample. During the FIB process, the choice of the pillar shape and the energy of the Ga ions can significantly impact the mechanical performance of samples with electron-transparent dimensions. Here, we systematically explore the effects of various pillar fabrication parameters in a single crystal aluminum (Al) system with a well-controlled crystal orientation. A novel method is proposed to fabricate square pillars to minimize FIB artifacts such as tapering, high pillar base compliance, and preferential deformation at the pillar tip. These square pillars enable more uniform deformation and accurate measurement of the engineering strain. Lastly, we show an intriguing in situ TEM laser irradiation experiment, which has enabled direct visualization of the surface oxide layer in FIB-fabricated Al pillars.

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Data and materials availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.


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This work was primarily supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under contract no. DE-AC02-05-CH11231 within the DamageTolerance in Structural Materials (KC 13) programme. S.Y.W. was supported by the National Science Foundation Graduate Research Fellowship (No. DGE 1752814). T.C.P. acknowledges funding from the DFG-project BR 5095/2-1 (Compressed sensing in ptychography and transmission electron microscopy). R.Z. and X.L. acknowledge funding from the US Office of Naval Research under Grant Nos. N00014-19-1-2376 and N00014-17-1-2283, respectively. The authors acknowledge support from the Molecular Foundry at Lawrence Berkeley National Laboratory, which is supported by the U.S. Department of Energy under Contract No. DE-AC02-05-CH11231. Pacific Northwest National Laboratory is operated for the U.S. DOE by Battelle Memorial Institute under Contract No. DE-AC05-76RLO1830. The authors thank Prof. Ju Li from MIT and Prof. Yongfeng Zhang from UW Madison for helpful discussions.


The authors declare no competing financial interests.

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Correspondence to Yang Yang or Andrew M. Minor.

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Yang, Y., Wang, S.Y., Xiang, B. et al. Evaluating the effects of pillar shape and gallium ion beam damage on the mechanical properties of single crystal aluminum nanopillars. Journal of Materials Research 36, 2515–2528 (2021).

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  • Transmission electron microscopy (TEM)
  • In situ
  • Nanoscale
  • Focused ion beam (FIB)
  • Defects
  • Al