Figure 6.

XRD patterns of NPs produced in run 6 sample (20.4 nm) at different reaction times:a2 h,b4 h, andc6 h showing different degrees of oxidation;dcolloidal sample produced in run 6 sample following oxidation in air at 200 °C for 2 h showing the conversion from wustite to a spinel structure (magnetite or maghemite), andecolloidal sample produced in run 6 sample following 40-day shelf time showing the conversion from wustite to a spinel structuree(magnetite or maghemite)

Chen et al. Nanoscale Research Letters 2009 4:1343-1350   doi:10.1007/s11671-009-9403-x