Room-temperature spontaneous magnetization in a nanostructured TiO2–Al system prepared by ball-milling

The change in the magnetic properties upon ball milling has been investigated for rutile TiO2 with Al powders. It has been found that nanostructured (TiO2)1−xAlx (x = 0–0.5) possesses room-temperature ferromagnetism after ball milling. The spontaneous magnetization depends on both Al content and milling time. Transmission electron microscopy and X-ray diffraction results show that the milled samples are mainly composed of nanostructured TiO2. X-ray absorption near-edge structures spectroscopy (XANES) has revealed that there is a charge transfer from Al to O at the interface of nanograins, suggesting that the charge-transfer ferromagnetism is a possible mechanism in the nanostructured TiO2–Al system.

► Spontaneous magnetization induced in TiO2–Al by ball milling.
► The spontaneous magnetization depends on both Al content and milling time.
► X-ray absorption near-edge structures suggest a charge transfer from Al to O at the interface of nanograins.
► Charge-transfer induced ferromagnetism is a possible mechanism.