Impact of Cr doping on the structure, optical and magnetic properties of nanocrystalline ZnO particles

The doping of Cr ions on the structure, optical and magnetic properties of ZnO have been investigated. Zn1-xCrxO (0 & LE; x & LE; 0.05) samples were prepared by the solution combustion method. Rietveld refined x-ray diffraction results reveal that all the samples are in a hexagonal structure. Transmission electron micro-scopy (TEM) revealed that the particle size was 48.2 & PLUSMN; 2.1 nm, 29.4 & PLUSMN; 2.2 nm and 25.3 & PLUSMN; 2.1 nm for the Zn1-xCrxO with x = 0, 0.03 and 0.05, respectively. The band-gap decreases slightly from 3.308 & PLUSMN; 0.003 eV to 3.291 & PLUSMN; 0.003 eV with increase of Cr content from x = 0 to 0.05, respectively. The field-dependent magne-tization M(& mu;& omicron;H) measurements of ZnO and Cr-doped ZnO exhibit room temperature ferromagnetism (RTFM). Photoluminescence and electron paramagnetic resonance exhibits negatively charged zinc va-cancies (VZn) and singly ionized oxygen vacancies (Vo+) in ZnO and these defects are responsible for RTFM. And the VZn accountable for RTFM in Cr-doped ZnO. EPR results confirmed that Cr3+ ions replaces the Zn2+ sites in the hexagonal ZnO. The observed long-range ferromagnetism ordering is explained based on the bound magnetic polaron (BMP) mechanism. This work elucidates the origin of RTFM in synthesized ZnO and Cr-doped ZnO.& COPY; 2023 Elsevier B.V. All rights reserved.

Automated summary

The effects of Cr ion doping on the structure, optical and magnetic properties of ZnO were investigated. Zn1-xCrxO (0 ≤ x ≤ 0.05) samples were prepared using the solution combustion method. X-ray diffraction results showed that all samples had a hexagonal structure. Transmission electron microscopy (TEM) revealed the particle size of Zn1-xCrxO with x = 0, 0.03 and 0.05 to be 48.2 ± 2.1 nm, 29.4 ± 2.2 nm, and 25.3 ± 2.1 nm, respectively. The band-gap slightly decreased from 3.308 ± 0.003 eV to 3.291 ± 0.003 eV with an increase in Cr content. Room temperature ferromagnetism (RTFM) was observed in ZnO and Cr-doped ZnO through magnetization measurements. The origin of RTFM was attributed to negatively charged zinc vacancies (VZn) and singly ionized oxygen vacancies (Vo+). The replacement of Zn2+ sites by Cr3+ ions in hexagonal ZnO was confirmed by electron paramagnetic resonance (EPR) results. The observed long-range ferromagnetic ordering was explained by the bound magnetic polaron (BMP) mechanism.