Shape-Evolution and Growth Mechanism of Fe₃O₄ Polyhedrons

Figure 3

SEM images of samples obtained using different amounts of NaOH: (a) 2.0 mmol (pH = 7), (b) 3.75 mmol (pH = 8), (c) 5.0 mmol (pH = 9), and (d) 12.5 mmol (pH > 14).

(a)

(b)

(c)

(d)