Size-Controlled Synthesis of CoFe₂O₄ Nanoparticles Potential Contrast Agent for MRI and Investigation on Their Size-Dependent Magnetic Properties

Figure 3

Control of the sizes of CoFe₂O₄/H⁺/citrate NPs by varying different parameters. The feeding orders of (a) and (b) were adding NH₄OH into (Co+Fe) and adding (Co+Fe) into NH₄OH, respectively, and the red/black line represented the results of varying [Co²⁺+Fe³⁺]/[OH⁻]; (c) and (d) show the change of CoFe₂O₄ NPs sizes by adjusting the pH of (Co+Fe) and the reaction temperature, respectively.

(a) Adding NH₄OH into (Co+Fe) of pH = 2

(b) Adding (Co+Fe) of pH = 2 into NH₄OH

(c) Adding NH₄OH into (1 M Co+2M Fe)

(d) Adding (1 M Co+2M Fe) into NH₄OH