Effect of strains on the optical and magnetic properties of Ce-doped ZnO with O or Zn vacancies

The magnetic and optical properties of Ce-doped ZnO systems have been widely studied; the effects of different strains on Ce-doped ZnO systems with O or Zn vacancies remain unclear. This study identified the effects of biaxial strain on the magnetic and optical properties of Ce-doped ZnO systems with O or Zn vacancies through a generalized gradient approximation + U method. Zn₁₅CeO₁₅ showed the best stability among Ce-doped ZnO systems with O vacancies when the distance between Ce atoms and O vacancies was 0.3801 nm. Zn₁₄CeO₁₆ showed the best stability among Ce-doped ZnO systems with Zn vacancies when the distance between Ce atoms and Zn vacancies was 0.3249 nm. The formation energy of Zn₁₅CeO₁₅ and Zn₁₄CeO₁₆ first increased and then decreased with increasing compressive strain, whereas that of Zn₁₅CeO₁₅ and Zn₁₄CeO₁₆ decreased with increasing tensile strain. The band gap of Zn₁₅CeO₁₆ and Zn₁₄CeO₁₆ widened and the absorption spectra blueshifted with increasing compressive strain. These findings will help with the design and preparation of new ZnO-based short-wavelength light-emitting diodes. The band gap of Zn₁₅CeO₁₆ and Zn₁₄CeO₁₆ narrowed and the absorption spectra redshifted with increasing tensile strain. These findings help with the design and preparation of novel ZnO-based photocatalysts. Zn₁₅CeO₁₆ and Zn₁₄CeO₁₆ showed room-temperature ferromagnetism in the absence of strain. The magnetic moments and Curie temperature of Zn₁₅CeO₁₆ and Zn₁₄CeO₁₆ decreased with increasing compressive and tensile strains. The Zn₁₅CeO₁₆ system was antiferromagnetic under − 5% compressive strain, whereas Zn₁₄CeO₁₆ system was antiferromagnetic under − 4% and − 5% compressive strain, and 4% and 5% tensile strain. The magnetic moment, Curie temperature, and ferromagnetism–antiferromagnetism of Zn₁₅CeO₁₆ and Zn₁₄CeO₁₆ can be controlled by strain. These results can serve as a reference for the design and preparation of Ce-doped ZnO magnetic materials and magnetic switches.