Ferromagnetism in ZnO Nanoparticles Induced by Doping of a Nonmagnetic Element: Al

The room-temperature ferromagnetism of Zn1−x Al x O nanoparticles synthesized by a sol−gel method is reported in this paper. X-ray diffraction and selected area electron diffraction results show that the Al atoms have successfully substituted for some of the Zn atoms in the ZnO lattice without forming other new phases. The results also show that the samples possess a typical wurtzite structure. Declaration of ferromagnetism at room temperature has been established with the observed hysteresis and the coercive field in hysteresis loops. Magnetic measurements indicate that the saturation magnetization of the samples is sensitive to the content of Al dopants and that, for Zn0.97Al0.03O, the saturation magnetization reaches the maximum of 0.012 emu/g. Combining with the results of Raman, photoluminescence, and X-ray photoelectron spectroscopies, it is suggested that the observed ferromagnetic ordering of the Zn1−x Al x O nanoparticles is related to the doping-induced oxygen vacancies.