Materials Research Letters (Jan 2021)

Gradient bandgap narrowing in severely deformed ZnO nanoparticles

  • Yuanshen Qi,
  • Yaron Kauffmann,
  • Anna Kosinova,
  • Askar R. Kilmametov,
  • Boris B. Straumal,
  • Eugen Rabkin

DOI
https://doi.org/10.1080/21663831.2020.1821111
Journal volume & issue
Vol. 9, no. 1
pp. 58 – 64

Abstract

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Gradient nanostructured metallic materials with a gradual change of grain boundary and dislocation density display unprecedent mechanical properties. Herein, we uncover a gradient of point defects concentration and concomitant gradient bandgap (Eg) narrowing in metal oxide nanoparticles processed by a combination of severe shearing and frictional sliding deformation. Using the valence electron-energy loss spectroscopy technique, we find a gradual decrease of Eg from 2.93 eV in the interior to 2.43 eV at the edge of the high-pressure torsion processed ZnO flake-shaped particle. This work paves the way to strain engineering of gradient-structured metal oxide semiconductors for unique functional properties. IMPACT STATEMENT We uncover a gradient of oxygen vacancy concentration and concomitant bandgap narrowing in an individual metal oxide nanoparticle processed by a combination of severe shearing and frictional sliding deformation.

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