Oxygen vacancy-mediated room temperature ferromagnetism in Sr-doped SnO2 nanoparticles
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Sn1−x Sr x O2 nanoparticles (NPs) were synthesized by the sol–gel method in the present work. X-ray diffraction analyses reveal that Sr atoms are incorporated into the SnO2 NPs without forming secondary phase with Sr concentration up to 5 at.%. The room temperature photoluminescence measurements indicate that Sr doping increases the number of singly charged oxygen vacancies (V O + ) in SnO2 NPs due to the different ionic radii of Sr2+ and Sn4+. Both pure and Sr-doped SnO2 NPs are ferromagnetic and the largest saturation magnetization of 6.98 × 10−4 emu/g has been observed in Sn0.95Sr0.05O2 NPs which has the largest concentration of V O + defects. The correlation between the induced V O + defects and the enhanced ferromagnetism implies that the observed ferromagnetic ordering in Sn1−x Sr x O2 NPs is connected with V O + defects. Meanwhile, air-annealing of the samples resulting in a significant suppression of the ferromagnetism further supports this point.
KeywordsSnO2 High Resolution Transmission Electron Microscopy Oxygen Vacancy High Resolution Transmission Electron Microscopy Physical Property Measurement System
This work was supported by the National Natural Science Foundation of China (51074112).