Influence of single-ionized oxygen vacancies on the generation of ferromagnetism in SnO2 and SnO2:Cr nanowires

Abstract

In this work, we report the influence of single-ionized oxygen vacancies ($$V^{\prime}_{{\text{O}}}$$ V O ′ ) as a spin ½ system in the ferromagnetic response of undoped and Cr-doped SnO2 nanowires. For this study, undoped and Cr-doped SnO2 nanowires were synthesized by a thermal evaporation method. Raman, Auger, and X-ray photoelectron spectroscopies confirmed the incorporation of Cr3+ ions in the SnO2 lattice. Electron paramagnetic resonance measurements demonstrated the presence of single-ionized oxygen vacancies ($$V^{\prime}_{{\text{O}}}$$ V O ′ ) in undoped and Cr-doped nanowires. Complementarily, cathodoluminescence measurements confirmed the presence of VO defects in the samples. Magnetic measurements revealed FM behavior from the undoped SnO2 and Cr-doped SnO2 nanowires, showing magnetization saturation values (MS) of ± 1 × 10–3 and ± 1.6 × 10–3 emu/g, respectively, and magnetic coercivity values (HC) of 180 and 200 Oe. We assign the FM response of nanowires to the presence of single ionized $$V^{\prime}_{{\text{O}}}$$ V O ′ acting as a spin ½ system and to the alignment of magnetic moments of Cr3+ ions, finding that $$V^{\prime}_{{\text{O}}}$$ V O ′ defects dominate in the FM generation.

Synthesis and Unique Behaviors of High-Purity HEA Nanoparticles Using Femtosecond Laser Ablation

“…A higher intensity of the peak at 532.2 eV, relative to the peak at 530.5 eV, suggests a greater proportion of oxygen vacancies. These vacancies can significantly change the material’s properties, such as its ability to conduct electricity, its magnetic behavior, and its catalytic activity in speeding up chemical reactions [ 45 , 46 , 47 , 48 ]. In this case, the ratio of oxygen vacancies to lattice oxygen is 0.78, indicating a substantial presence of oxygen vacancies in the material.…”