Vanadium dioxide nanobelts: Hydrothermal synthesis and magnetic properties

VO2 (B) nanobelts were prepared by a hydrothermal method at 180 °C using V2O5·nH2O sol and H2C2O4·2H2O as starting agents. The obtained nanobelts have diameters ranging from 50 to 100 nm in width, 20–30 nm in thickness with lengths up to 1.5 μm. Measurements of the static magnetic susceptibility provide evidence for two phase transitions at T1 = 225 K and T2 = 290 K, respectively. Below T1, the data suggest the presence quasi-free as well as of strongly antiferromagnetic correlated spins associated to V4+-ions.