The microstructures and magnetic properties of nickel ferrite synthesized by coprecipitation and sol–gel methods are comparatively studied. The coprecipitation-derived samples have Fe/Ni ratios differing from their raw materials because of the precipitation washing process. The stoichiometric metal cations (Fe/Ni=2.0) in the xerogel facilitated the nucleation and growth of nickel ferrite nanocrystallites at lower calcination temperature in sol–gel method. The samples consist of nickel ferrite nanocrystallites, and have superparamagnetic properties at room temperature.

Leaves, which are very easy to obtain freely, can be used as raw materials to prepare carbon materials. In this paper, we found that hard carbon can be prepared from willow leaves by one-step carbonization. When the hard carbon was used as anode materials for Li-ion batteries, the revisable capacity of the hard carbon was 230-260 mAhg-1 at the current density of 37.2 mAg-1 with a first-cycle coulombic efficiency of about 50 %. In addition, the hard carbon shows stable cycling performance and good rate capability.