Gradient bandgap narrowing in severely deformed ZnO nanoparticles

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

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 (E g) 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 E g 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.

Original languageEnglish
Pages (from-to)58-64
Number of pages7
JournalMaterials Research Letters
Volume9
Issue number1
DOIs
StatePublished - 2 Jan 2021

Keywords

  • Bandgap
  • STEM-EELS
  • ZnO
  • gradient-structured materials
  • high-pressure torsion

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