The investigation of the maximum doping concentration of iron in zinc sulfide nanowires, and its optical and ferromagnetic properties

The wurtzite-type ZnS:Fe2+ nanowires were prepared by a hydrothermal method at 180 °C without any surface-active agent. The results showed that the average diameter of the nanowires was about 10 nm. The Fe2+ ions were substitutionally incorporated into the ZnS host and the maximum concentration of the Fe2+ ions in the ZnS nanowires can reach to 5.81%. The absorption peak exhibited a small red-shift as the Fe doped ratio increased, which may be due to the increased size of the nanowires. After adding Fe2+ ions into the ZnS nanowires, no Fe-related emission peak can be observed and the emission intensity was quenched, indicating that the Fe2+ ions only acted as the nonradiative center. The ferromagnetism of the ZnS:Fe2+ nanowires was observed around room temperature, the mechanism of which was explained by the super-exchange mechanism.

► The maximum concentration of Fe ions in the ZnS nanowires is 5.81%. ► The Fe2+ ions act as the nonradiative center for the ZnS:Fe2+ nanowires. ► We observe the room temperature ferromagnetism for the ZnS:Fe2+ nanowires.