UV-irradiation-enhanced ferromagnetism of barium vanadate (Ba3V2O8) nanoflowers

Both enhanced saturation magnetization and coercivity of the flower-shaped hexagonal Ba3V2O8 with a small amount of Ba3VO4.8 in coexistence have been investigated after UV irradiation. The barium vanadate flower is composed of nanosheets with thickness of similar to 20 nm. The optical absorption edge changes from 3.85 eV to 3.67 eV after UV irradiation and absorption intensity becomes stronger. The mechanism of magnetic property change is discussed via density functional theory. The result shows that oxygen vacancy produces impurity level within the forbidden energy gap, leading to red shift of optical absorption edge and reduction of V atom from +5 to +4. This study gives a good understanding of the magnetic property induced by the valence state change in Ba3V2O8 nanostructure under the UV irradiation and provides a new route to obtain diluted magnetic semiconductors. (C) 2012 Elsevier B.V. All rights reserved.