(Color online) TEM images and magnetization of freestanding (▴) and aggregated (엯) 0.93% nanocrystals. Adapted from Ref. 14.
(Color online) magnetization of 0.48% nanocrystals annealed aerobically for 0 (엯) and 11 (●) min at .
(Color online) ferromagnetic saturation moment (엯) and relative paramagnetism (▴) of 0.48% nanocrystals collected as a function of annealing time at under air. Bottom: TGA data for the same sample under the same conditions, showing no loss of mass. Adapted from Ref. 11.
(Color online) ferromagnetic saturation moment (엯) and relative paramagnetism (▴) of 0.48% nanocrystals as a function of annealing time at under inert atmosphere . Adapted from Ref. 11.
(Color online) Top: schematic representation of the activation and deactivation of ferromagnetism in mildly heated NCs shown in Figs. 3 and 4. The nonstoichiometric oxygen vacancy defects formed at fusion grain boundaries during annealing are passivated under aerobic conditions and ferromagnetism is deactivated. Bottom: magnetic phase diagram (adapted from Ref. 8), where is the volume of the defect hydrogenic wave function and is the defect concentration. In the data of Fig. 3, increases with defect formation and then decreases with defect passivation, all at constant concentration. In the data of Fig. 4, increases with defect formation, but no passivation occurs in the inert atmosphere .
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